Instrumentation and procedure for implanting spinal implant devices

ABSTRACT

An implant may be formed in a disc space between vertebrae using instruments in an instrumentation set. In some embodiments, the implant may be formed from individual pieces including implant members and connectors. After formation of the implant, the implant may be set using a seater. The seater may fix the position of pieces of the implant relative to each other to inhibit separation of the pieces. The seater may apply force to pieces of the implant. The force applied to the pieces may deform the pieces sufficiently to inhibit subsequent separation of the pieces from each other.

PRIORITY CLAIM

[0001] This application claims priority to U.S. Provisional ApplicationNo. 60/363,219 entitled “Instrumentation And Procedure For ImplantingFusion Devices,” filed Mar. 11, 2002. The above-referenced provisionalapplication is incorporated by reference as if fully set forth herein.

BACKGROUND

[0002] 1. Field of the Invention

[0003] The present invention generally relates to the field of medicalimplants and more particularly to instruments used to insert spinalimplants. An embodiment of the invention relates to instruments that maybe used to set a spinal implant that has been positioned in a disc spacebetween adjacent vertebrae so that separation of the implant intoseparate pieces is inhibited.

[0004] 2. Description of Related Art

[0005] An intervertebral disc may be subject to degeneration.Degeneration may be caused by trauma, disease, and/or aging. Anintervertebral disc that becomes degenerated may have to be partially orfully removed from a spinal column. Partial or fill removal of anintervertebral disc may destabilize the spinal column resulting insubsidence or deformation of vertebrae. Destabilization of a spinalcolumn may result in alteration of a natural separation distance betweenadjacent vertebrae. Maintaining the natural separation between vertebraehelps to prevent pressure from being applied to nerves that pass betweenvertebral bodies. Excessive pressure applied to the nerves may causepain and/or nerve damage. During a spinal fixation procedure, a spinalimplant may be inserted within a space created by the removal or partialremoval of an intervertebral disc between adjacent vertebrae. The spinalimplant may maintain the height of the spine and restore stability tothe spine. The spinal implant may be a fusion device. Intervertebralbone growth may fuse the implant to adjacent vertebrae. The spinalimplant may be an artificial disc.

[0006] A spinal implant may be inserted during a spinal fixationprocedure using an anterior, lateral, or posterior spinal approach. Ananterior spinal approach may be a preferred method for some spinalimplant procedures. An anterior spinal approach may require less boneremoval and muscle distraction than a posterior spinal approach. Inaddition, an anterior spinal approach may involve less risk of nervedamage than a posterior spinal approach.

[0007] During an anterior spinal approach, a surgical opening may bemade in the abdomen of a patient. This opening may extend from theabdomen to an anterior surface of the spine. For some patients, theopening may be ten or more inches in depth. The opening needs to belarge enough to accommodate instrumentation for insertion of a spinalimplant within a disc space. A discectomy may be performed to remove orpartially remove a defective or damaged intervertebral disc. Thediscectomy creates a disc space for a spinal implant. The amount ofremoved disc material may correspond to the size and type of a spinalimplant to be inserted.

[0008] A type of spinal implant used to promote fusion of adjacentvertebrae may include a pair of engaging plates and struts. Struts maybe positioned between the engaging plates to establish a separationdistance between the engaging plates. Spinal implants having engagingplates and struts are described in U.S. Pat. No. 6,045,579 issued toHochschuler et al., which is incorporated by reference as if fully setforth herein. Struts may separate and join engaging plates of anassembled spinal implant. The engaging plates may provide a largecontact area between the spinal implant and vertebrae that are to befused together. The large contact area may minimize subsidence anddeformation of the vertebrae during use. The engaging plates may includeprotrusions that inhibit migration of the inserted implant. Eachengaging plate may also include several openings to promote bone growththrough the spinal implant to fuse the adjacent vertebrae together. Thespinal implant may be formed in the disc space so that noover-distraction of the adjacent vertebrae is needed.

[0009] The engaging plates and struts may allow an anterior height of aspinal implant to differ from a posterior height of the implant. Theavailability of spinal implants that have different anterior andposterior heights may allow a surgeon to choose a spinal implant thatwill provide proper lordotic alignment and vertebral separation for aparticular patient.

[0010] The struts of a spinal implant establish a separation distancebetween the engaging plates of the implant. The separation distancebetween the engaging plates may in turn establish a desired separationdistance between adjacent vertebrae when the implant is formed betweenthe vertebrae. Establishing a desired separation distance betweenengaging plates and adjacent vertebrae may establish a proper distancebetween vertebral bodies.

[0011] The struts of a spinal implant may include load-sharing members.The load-sharing members may allow a portion of a load placed on theimplant to be transmitted to bone growth material placed within theimplant. The transmittal of a portion of a load to bone growth materialmay promote bone growth in accordance with Wolff's law. Bone growththrough and around a spinal implant may fuse the adjacent vertebraetogether. Bone growth material inserted into the implant may be, but isnot limited to, autograft bone harvested from a secondary location, suchas the iliac crest; allograft material; or artificial bone growthmaterial.

[0012] Another type of spinal implant may include a cage into which bonegrowth material is placed. A method of inserting the spinal implant mayinclude forming a disc space that is slightly smaller than a height ofthe spinal implant and impacting the implant into the opening. Impactingan implant may be dangerous and may not inhibit an inserted implant frombacking out of a disc space after insertion. An alternate method ofinserting a spinal implant may involve forming a disc space that isslightly larger than a height of the implant to be inserted into thedisc space by distracting the vertebrae with a distraction device. Aftera spinal implant is inserted, the distraction device may be removed.Distracting the adjacent vertebrae a distance that allows a spinalimplant to be inserted into a disc space, however, may not be desirable.Imperfect elastic characteristics of connective tissue may not allowconnective tissue to return to a pre-distracted state after thedistraction device is removed.

[0013] Another type of spinal implant includes threading along asubstantial portion of a length of the implant. The implant may bescrewed into a prepared opening between adjacent vertebrae. The threadedimplant may include self-tapping threads, or the spinal implant may bethreaded into a tapped opening.

SUMMARY

[0014] Instruments of an instrumentation set may be used to form a boneimplant within a space between two bones of a patient. Theinstrumentation set may include a seater that sets an implant formedwith other instruments so that separation of the implant into pieces isinhibited. Instruments of the instrumentation set may allow asignificant portion of positioning and manipulation to be affected fromabove an incision in a patient. Instruments of the instrumentation setmay allow for insertion of a bone implant in a simple, efficient, andsafe manner. In an embodiment, the bone implant is a spinal implantformed in a disc space between adjacent vertebrae. In other embodiments,the bone implant may be an implant placed in a space formed between twoportions of a bone. The bone may be shorter than a desired length. Thebone implant may be used to establish a desired length of bone.Instruments of the instrumentation set may require a small opening inthe patient while still allowing ample visibility of a surgical site, animplant, and instruments during the insertion procedure.

[0015] Bone implants may be made from a wide variety of materials. Boneimplants may be formed from, but are not limited to being formed from,metal, ceramics, bone, polymers, or combinations thereof. In anembodiment, a bone implant is made of a titanium alloy (such asTi6AL4V). Portions of a bone implant that contact bone may be coatedwith a material, such as, but not limited to, titanium plasma spray,bone morphogenic proteins, and/or hydroxyapatite to promoteosseointegration. In addition to, or instead of, coating portions of thebone implant that contact bone, portions of the bone implant thatcontact bone may be roughened to promote osseointegration. The portionsmay be roughened by any of several processing techniques, including, butnot limited to, chemical etching, surface abrading, shot peening, anelectric discharge process, and/or embedding particles in the surface.

[0016] A bone implant, or a portion of a bone implant, may be made of abiodegradable and/or bioabsorbable material. For example, a polymer usedto form a bone implant, or a portion of a bone implant, may be, but isnot limited to, a polyanhydride, an alpha polyester, and/or a polylacticacid-polyglycolic acid copolymer.

[0017] An instrumentation set for a spinal implant insertion proceduremay include various insertion instruments. The insertion instruments mayinclude, but are not limited to, a spreader, a separator, and a strutseater. The instrumentation set may also include spinal implantcomponents. The implant components may include, but are not limited to,implant members of various sizes and lordotic alignment and connectorsof various sizes. A spreader may allow implant members that form aspinal implant to be positioned between two adjacent vertebrae. Aseparator may be positioned between the implant members to establish adesired separation distance between the implant members. In anembodiment, a connector or connectors may be inserted through theseparator and into the implant members. The connectors may join theimplant members together.

[0018] A spreader may allow implant members to be positioned within aprepared disc space between vertebrae. The spreader may be sufficientlylong to allow easy placement of a distal end of the spreader in the discspace from above an incision in a patient. The spreader may includeholders that secure implant members of a spinal implant to the spreader.The holders and attached implant members may be positioned in a discspace during an anterior spinal implant insertion procedure. A distancebetween the holders may be adjusted by inserting a separator into thespreader. The separator may establish a desired separation distancebetween outer surfaces of the implant members without excess distractionof the vertebrae.

[0019] In addition to establishing a desired separation distance betweena pair of implant members, a separator may include passages that conductconnectors to the implant members. The connectors may fix the separationdistance between the implant members. In an embodiment of a spinalimplant, implant members may include slots. Portions of connectors maybe positioned in the slots to join the implant members together.

[0020] An embodiment of a spreader may have implant holders. An openingor openings in the implant members may press-fit onto the implantholders. Locking pins may be inserted into slots of the spreader andinto implant member slots to secure the spreader to the implant membersand to maintain proper alignment of the spreader slots with respect tothe implant member slots. In an alternate embodiment, a spreader mayhave implant holders that are inserted into dovetail channels of theimplant members. When the spreader is fully inserted into the dovetailchannels, implant member slots will align with slots in the spreader.Gaps in the implant holders may be compressed when the spreader isinserted into the dovetailed channels. A force exerted by arms tocounter the compression of the gaps may hold the implant members on thespreader. Alternatively, the implant holders may have spring membersthat fit into an opening in the implant members and apply a force to thedovetailed channels to hold the implant members on the spreader.

[0021] During some implant insertion procedures, a disc space may be toosmall to allow for insertion of implant members coupled to a spreaderwithout protrusions of the implant members scarring surfaces of adjacentvertebrae during insertion. In some embodiments, distractors may be usedto separate vertebrae to a distance that is less than the desiredseparation distance to be established by the spinal implant. The spinalimplant may then be formed in the disc space.

[0022] In other embodiments, insertion guides may be positioned in adisc space that is too small to allow for insertion of implant members.The insertion guides may include stops that limit an insertion depthinto the disc space. After placing insertion guides in the disc space, aspreader with attached implant members may be inserted into the discspace between the insertion guides. The insertion guides may be removedafter insertion of the implant members and spreader.

[0023] Insertion of a separator in a spreader may force outer surfacesof implant members against vertebrae. Continued insertion of theseparator into the spreader may drive protrusions of the implant membersinto vertebral bone. The separator may be impacted into the spreaderusing a mallet or a slap hammer. The separator may establish a desiredseparation distance between vertebrae.

[0024] After establishing a separation distance between vertebrae byinserting a separator into a spreader, connectors may be positioned inimplant member slots to join implant members together. After insertionof the connectors into the implant members, the spreader and theseparator may be removed from between the vertebrae.

[0025] A connector seater may be coupled to the implant members and to aconnector or connectors. The connector seater may apply force to theimplant members and the connector or connectors to affix the connectoror connectors to the implant members. The force applied by the connectorseater to the implant members and the connectors may be sufficient todeform implant member slots and/or portions of the connectors to affixthe connectors to the implant members. The connector seater may includean indicator to indicate when a sufficient amount of force has beenapplied to the connectors and the implant members. After connectors areaffixed to implant members, the connector seater may be removed from anopening in a patient. Bone growth material may be placed in a spacebetween the implant members before the opening is closed.

[0026] The connectors may allow for minor adjustment of a distanceseparating the implant members so that the implant members apply acompressive load to bone growth material positioned between the implantmembers. If a large compressive force is applied to the implant members,the connectors and implant members may act as a single unit thatdissipates the force over the large surface area of the implant members.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Advantages of the present invention will become apparent to thoseskilled in the art with the benefit of the following detaileddescription of embodiments and upon reference to the accompanyingdrawings in which:

[0028]FIG. 1 shows a perspective view of an embodiment of a spinalimplant.

[0029]FIG. 2 shows a perspective view of an embodiment of a spinalimplant.

[0030]FIG. 3 shows a plan view of an intervertebral disc space betweenadjacent vertebrae.

[0031]FIG. 4 shows a top view of a spinal implant positioned betweenadjacent vertebrae.

[0032]FIG. 5 shows a perspective view of an embodiment of an engagingplate that emphasizes an inner surface the engaging plate.

[0033]FIG. 6 shows a perspective view of an embodiment of a connector.

[0034]FIG. 7 shows a perspective view of an embodiment of a connector.

[0035]FIG. 8 shows a perspective view of an embodiment of a backingplate.

[0036]FIG. 9 shows a perspective view of an embodiment of a width anddepth spacer.

[0037]FIG. 10 shows a perspective view of an embodiment of a heightspacer.

[0038]FIG. 11 shows a perspective view of an embodiment of a separator.

[0039]FIG. 12 shows a perspective view of an embodiment of a separator.

[0040]FIG. 13 shows a perspective view of an embodiment of a spreaderwith plate holders in a spread apart position.

[0041]FIG. 14 shows a perspective view of an embodiment of a spreaderwith plate holders in an initial position.

[0042]FIG. 15 shows a perspective view of an embodiment of an integralhandle and plate holder combination.

[0043]FIG. 16 shows a perspective view of a portion of an embodiment ofa spreader with engaging plates coupled to the spreader.

[0044]FIG. 17 shows a perspective view of an embodiment of an innersurface of a member holder.

[0045]FIG. 18 shows a perspective view of a portion of an embodiment ofa spreader that emphasizes a front view of a member holder.

[0046]FIG. 19 shows a side view of a portion of an embodiment of aspreader.

[0047]FIG. 20 shows a perspective view of an embodiment of a locking pinwith a detail of a tip of the locking pin.

[0048]FIG. 21 shows a perspective view of an embodiment of an extender.

[0049]FIG. 22 shows a perspective view of an embodiment of a mallet.

[0050]FIG. 23 shows a partial view of an embodiment of a spreader,separator, implant member, and locking pin combination, wherein thedepicted portion of the separator is shown in cross section.

[0051]FIG. 24 shows a partial perspective view of an embodiment of aspreader and separator combination prior to release of a connector intoa connector passage of the separator.

[0052]FIG. 25 shows a partial view of an embodiment of a spreader,separator, implant member, and connector combination, wherein thedepicted portions of the connectors and separator are shown in crosssection.

[0053]FIG. 26 shows a perspective view of an embodiment of a depthgauge.

[0054]FIG. 27 shows a perspective view of an embodiment of a slaphammer.

[0055]FIG. 28 shows a cross-sectional representation of a portion of aslap hammer.

[0056]FIG. 29 shows a perspective view of a portion of a slap hammerembodiment.

[0057]FIG. 30 shows a perspective view of an embodiment of a separator.

[0058]FIG. 31 shows a plan view of an embodiment of a separator.

[0059]FIG. 32 shows a perspective view of an embodiment of a depthgauge.

[0060]FIG. 33 shows a perspective view of an embodiment of a separatorwith a connector inserted into one side opening and a second connectorpositioned above a second side opening.

[0061]FIG. 34 depicts a perspective view of an embodiment of a depthgauge.

[0062]FIG. 35 depicts a perspective view of a portion of an embodimentof a separator that may be used with the slap hammer embodiment depictedin FIG. 29.

[0063]FIG. 36 shows a perspective view of an embodiment of a spreader.

[0064]FIG. 37 shows a perspective view of a portion of an embodiment ofa spreader emphasizing an outer surface of a member holder.

[0065]FIG. 38 shows a perspective view of a portion of an embodiment ofa spreader that emphasizes a member holder.

[0066]FIG. 39 shows a perspective view of an embodiment of an end capfor a spreader.

[0067]FIG. 40 shows a perspective view of an embodiment of an insertionguide.

[0068]FIG. 41 shows a perspective view of an embodiment of an insertionguide.

[0069]FIG. 42 shows a perspective view of an embodiment of an insertionguide inserted between vertebrae.

[0070]FIG. 43 shows a perspective view of an embodiment of a spreaderwith attached implant members positioned between arms of an insertionguide.

[0071]FIG. 44 shows a perspective view of an embodiment of a spreaderwith attached implant members after removal of arms of an insertionguide.

[0072]FIG. 45 shows a perspective view of an embodiment of a spreaderwith an end cap inserted into an opening of the spreader.

[0073]FIG. 46 shows a perspective view of an embodiment of a combinationslap hammer, separator, spreader, and depth gauges.

[0074]FIG. 47 shows a perspective view of an embodiment of a connectorseater.

[0075]FIG. 48 shows a perspective view of a portion of an embodiment ofa connector seater.

[0076]FIG. 49 shows a perspective view of an embodiment of a retainer.

[0077]FIG. 50 shows a perspective view of an embodiment of a retainer.

[0078]FIG. 51 shows a cross-sectional representation of an embodiment ofa seater.

[0079]FIG. 52 shows a cross-sectional representation of an activationportion of an embodiment of a seater.

[0080]FIG. 53 shows a perspective view of an embodiment of a connectorattached to a calibrator.

[0081]FIG. 54 shows a perspective view of an embodiment of a seater.

[0082]FIG. 55 shows a perspective view of a portion of a seater andretainer combination.

[0083] While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof are shown by way ofexample in the drawings and will herein be described in detail. Thedrawings may not be to scale. It should be understood, however, that thedrawings and detailed description are not intended to limit theinvention to the particular form disclosed, but to the contrary, theintention is to cover all modifications, equivalents, and alternativesfalling within the spirit and scope of the present invention as definedby the appended claims.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0084] Referring to the drawings, FIG. 1 and FIG. 2 show perspectiveviews of embodiments of implants 10. An implant may include members anda spacer between the members. The members may be implant members thatcontact surfaces of bone that are to be joined together by the implant.The spacer may establish a desired distance between the members. Thespacer may be a formed of one or more components. In some embodiments,implant 10 may be a spinal implant. In some embodiments, the spinalimplant may be a fusion device that promotes bone growth betweenvertebrae to fuse the vertebrae together. In some embodiments, thespinal implant may be an artificial disc that joins two vertebraetogether while still allowing for at least some motion of the vertebraerelative to each other. In some embodiments, the implant may be animplant that joins and promotes fusion of two portions of a bone (e.g.,a femur).

[0085] Implant 10 may include a pair of implant members 12 and connectoror connectors 14 that couple the implant members together. In anembodiment of implant 10, implant members 12 may be a pair of engagingplates and connectors 14 may be struts.

[0086]FIG. 3 depicts disc space 16 between adjacent vertebrae 18.Apportion or all of intervertebral disc 20 may be removed betweenadjacent vertebrae 18 during a discectomy that forms disc space 16.

[0087]FIG. 4 depicts an embodiment of implant 10 inserted in disc space16 formed in intervertebral disc 20. Implant 10 may provide spinalcolumn stability and promote bone growth that fuses adjacent vertebrae18 together.

[0088]FIG. 5 shows an embodiment of implant member 12 emphasizing innersurfaces of the implant member. FIG. 6 and FIG. 7 show embodiments ofconnectors 14. Implant members and connectors may be made of anybiocompatible material, including, but not limited to, titanium,titanium alloy, stainless steel, ceramic material, bone, polymers, orcombinations thereof. In an embodiment, implant members are formed of atitanium and aluminum alloy, such as Ti6Al4V-Eli. An instrumentation setfor a spinal insertion procedure may include a number of different sizesof implant members. Pairs of implant members included in aninstrumentation set may have

[0089] An instrumentation set may include implant members. Implantmembers having different surface areas that will contact or be adjacentto bone when inserted into a patient may be provided in theinstrumentation set. For example, an instrumentation set may includelarge, medium, and/or small size implant members. Surface areas of largeimplant members that will contact or be adjacent to bone when insertedinto the patient are larger than similar surface areas of medium implantmembers, which are larger than similar surface areas of small implantmembers. A surgeon may determine which size of implant members to useprior to or during the implant insertion procedure. A pair of implantmembers of the same size may form a part of an implant that is formed ina patient.

[0090] Outer surface 22 of implant member 12 (shown in FIG. 1 and FIG.2) may include a coating or outer layer, such as, but not limited to, atitanium plasma spray, bone morphogenic proteins, and/or hydroxyapatite.The coating may promote osseointegration. Osseointegration refers to ahealing process that results in the formation of connecting bone thatattaches an object to the bone. The object may be an implant or aportion of an implant.

[0091] In addition to, or instead of, coating outer surfaces 22, theouter surfaces may be roughened to promote osseointegration of theimplant members to adjacent vertebrae. Outer surfaces 22 of implantmember 12 may be roughened by any of several processing techniques,including, but not limited to, chemical etching, surface abrading, shotpeening, using an electric discharge process, or embedding particles inthe surface.

[0092] Outer surface 22 of implant member 12 may have a large surfacearea so that there is a large contact area between implant member 12 andan adjacent vertebra. The large contact area may minimize subsidenceand/or deformation of the vertebrae that implant I0 contacts.

[0093] As shown in FIG. 1 and FIG. 2, implant member 12 may include aplurality of protrusions 24 on outer surface 22. Protrusions 24 offormed implant 10 may extend into adjacent vertebrae to securely fastenthe implant to the adjacent vertebrae. In an embodiment, protrusions 24are arranged in two radial rows each containing 6 protrusions. Otherarrangements with fewer or more protrusions may also be used.Protrusions 24 may extend about 0.2 mm or more from outer surface 22 ofimplant member 12. In an embodiment, protrusions 24 extend approximately1 mm from outer surface 22. Protrusions 24 may anchor the implant memberto surfaces of vertebrae. Outer surface 22 of implant member 12 mayinclude curvature. The curvature may allow outer surfaces 22 of implantmembers 12 to substantially conform to shapes of vertebral surfaces. Forexample, outer surface 22 of an implant member may conform to ananatomical dome of a vertebra.

[0094] Embodiments of implant members 12 may include sloped outersurfaces 22. The sloped outer surfaces may allow an anterior height ofassembled implant 10 to differ from a posterior height of the implant.Several different pairs of implant members 12 having different slopedouter surfaces 22 may be included in an instrumentation set provided toa surgical team that will perform an implant insertion procedure on apatient. The availability of implant members 12 of differing slopes mayallow a surgeon to form implant 10 that will provide proper lordoticalignment for the patient. In an embodiment of an instrumentation set,implant members 12 provided in the instrumentation set have slopes thatrange from about 0° to about 9° in approximately 30 increments. Thisallows a surgeon to form implant 10 with lordotic adjustment from about0° (wherein each implant members has 0° of lordotic angle) to about 180of lordotic adjustment (wherein each implant member has 9° of lordoticangle). In some embodiments, implant members with differing amounts oflordotic angle may be used to provide a desired amount of lordoticadjustment. For example, a lordotic adjustment of about 9° may beobtained by forming an implant using an implant member with 9° oflordotic angle and a second implant member having 0° of lordotic angle.Lordotic adjustment of 9° may also be obtained by forming an implantusing an implant member with 6° of lordotic angle and an implant memberhaving 3° of lordotic angle. In an alternate embodiment of implant 10,connector or connectors 14 may include a sloped surface to providelordotic adjustment. In other embodiments, other ranges and incrementsof slopes of implant members and/or connectors may be provided.

[0095] Implant members may be color-coded and/or include indicia. Thecolor-coding and/or indicia may indicate a size of a particular implantmember. For example, an implant member may be stamped with the letter“M” to indicate that the implant member is a medium sized implantmember. Similarly, an implant member may be color-coded and/or includeindicia to indicate an amount of lordotic angle that the implant memberhas.

[0096] When implant 10 is positioned between adjacent vertebrae 18, asrepresented in FIG. 4, bone growth material 26 may be packed between twoimplant members 12 coupled by connector or connectors 14. Bone growthmaterial 26 may be, but is not limited to, autograft bone (such as bonefrom the patient's iliac crest), allograft bone, synthetic bone growthmaterial, or combinations thereof.

[0097] As depicted in FIG. 1, FIG. 2, and FIG. 5, implant member 12 mayinclude a plurality of openings 28. Openings 28 in upper implant member12′ may vertically align with openings in lower implant member 12” ofimplant 10 when the implant is formed in a disc space. Bone may developthrough openings 28 to fuse the vertebrae together. Bone graft maypromote fusion of adjacent vertebrae. Some openings 28 may have recessedsurfaces 30, as shown in FIG. 1.

[0098]FIG. 5 shows a perspective view of implant member 12 thatemphasizes inner surfaces of the member. Each implant member 12 mayinclude tapered slots 32. Slots 32 may be widest proximate anterior side34 of implant member 12. Sidewalls 36 of slots 32 may be angled, ordovetailed, so that the slots are wider at their bases than at insidesurfaces of implant members 12.

[0099] As depicted in FIG. 5, implant member 12 may also includerecessed surface 38. Recessed surface 38 may begin at anterior side 34of implant member 12 and stop before reaching posterior side 40 of theimplant member. In an embodiment, the sidewalls of recessed surface 38are substantially straight. In other embodiments, the sidewalls ofrecessed surface 38 may be dovetailed, or of any other appropriate shapefor coupling implant member 12 to an insertion tool.

[0100]FIG. 6 and FIG. 7 show embodiments of connector 14. Connector 14may be a strut. Connector 14 may have tapered end surfaces 42 and angledside portions 44. Tapered end surfaces 42 of connector 14 may bepositioned in tapered slots of implant members. The taper of tapered endsurface 42 may substantially correspond to the taper of implant memberslots 32 (shown in FIG. 5), so that there is a large contact areabetween an implant member and a connector inserted into the implantmember. The angle of sides 44 may correspond to the angle of taperedslot sides in an implant member. The tapered shape of the slots of theimplant members and tapered end surfaces 42 of connectors 14 may onlyallow removal of the connectors from the implant member in a reversemanner to the insertion of the connectors into the slots. When it isdesired to affix connectors to implant members, large forces may beapplied to the connectors and the implant members to deform the taperedslots and/or connectors so that removal of the connectors is prevented.

[0101] A frictional connection may be formed between connector 14 andimplant members across a large contact area when the connector is fullyinserted into slots of the implant members. In another embodiment,connectors 14 may be attached to implant members by means other thanfrictional engagement. For example, an interference fit may be formedbetween a connector and implant members. Channels that hold theconnectors within the implant members may include projections that fitwithin indentions in the connector to form an interference fit when theconnector is fuilly inserted into the channel of the implant member.Alternately, the channels that hold connectors 14 within the implantmembers may include indentions that form an interference fit withprojections extending from the connector when the connector is fullyinserted into the channel of the implant members. An amount of forceneeded to insert connector 14 fully within the channel of the implantmembers may inhibit unintentional full insertion of the connector intothe implant members. The interference fit may inhibit removal ofconnector 14 from the implant members when the connector is fullyinserted into the implant members.

[0102] An embodiment of connector 14, such as the connector embodimentdepicted in FIG. 6, may include first member 46, second member 48, andpin 50. Assembled connector 14 may be held together by setscrew 52.Assembled connector 14 may be positioned between implant members.Connectors 14 may be provided in an instrumentation set for a spinalinsertion procedure in various sizes. For example, an instrumentationset may be provided with connectors for medium and large implantmembers. An instrumentation set may include connectors that formimplants with separation distances between implant members ranging fromabout 8 mm to about 16 mm in approximately 2 mm increments. Other sizeranges and/or size increments of connectors 14 may be provided.

[0103] Pin 50 may hold first member 46 to second member 48. Setscrew 52may contact and apply force against pin 50. The force may inhibitremoval of pin 50 from first member 46 and second member 48. Firstmember 46 may be able to rotate relative to second member 48. Thepin-type of connection in connectors 14 may allow connectors ofdifferent sizes to be inserted into implant members. The resultingimplant may have different heights at medial and lateral ends of theformed implant. In other embodiments, implant members may be formed withdifferent medial and lateral heights so that a resulting implant willhave different heights at medial and lateral ends of the implant, whileeach connector used to form the implant has substantially the sameheight.

[0104] After formation of an implant in a patient, compressive forcesmay be applied to implant members of the implant. Compressive forcesapplied to the implant members may deflect pin 50 of connector 14 andallow the first implant member of the implant to move a small distancetowards the second implant member of the implant. As such, some of thecompressive force applied to the implant members may be transferred tobone growth material positioned between the implant members. Applicationof stress to the bone growth material may promote formation of bone thatfuses together the vertebrae joined by the implant. Bone needs toundergo stress to maintain normal density. A bone's strength and healthis directly related to its density. When bone is not stressed, or isshielded from stress, it may lose density and resorb into the body.

[0105] Application of compressive forces to an implant that exceed aforce to which a spinal column is normally exposed may cause connectormembers 46, 48 and pin 50, shown in FIG. 6, to act as a single, solidmember. The single, solid member may not allow the implant members to becompressed towards each other closer than a predetermined spacing.Excessive force applied to the vertebrae may cause bone fracturesadjacent to the implant. A large contact surface between the implant andthe vertebrae may promote dissipation of large forces over largevertebral areas so that bone fracturing is inhibited. Repetitiveapplication of large forces to bone growth material may inhibitformation of connecting bone and promote formation of a fibrous mass.Limiting movement of implant members towards each other may inhibitapplication of excessive forces to bone growth material placed betweenthe implant members.

[0106]FIG. 7 depicts an alternate connector embodiment. Connector 14 mayinclude flexible member 54, limiters 56, and pins 58. Pins 58 may couplelimiters 56 to flexible member 54. Pins 58 may be press-fit, threaded,welded, glued, or otherwise attached to flexible member 54. Compressiveforces applied to implant members of a formed implant may compressflexible member 54, allowing some of the force to be shared by bonegrowth material located between the implant members. Limiters 56 aresized so as not to allow flexible member 54 of connector 14 to becompressed towards each other closer than a predetermined spacing.

[0107] Connectors 14 and limiters 56 of an implant may selectivelycontrol the amount of strain applied to bone growth material placedwithin the implant. For example, connectors 14 may limit the totalstrain on the bone growth material within the implant to less than about0.5% of the strain applied to the implant members. Excessive strain onthe bone growth material, for example, greater than about 1% of thestrain applied to the implant members, may cause the bone growthmaterial to form a fibrous mass instead of bone. Connectors 14 may bemade of a relatively rigid material, such as medical grade titanium.Connectors 14 may shield the bone growth material and support a largeportion (over 99%) of the strain applied to the implant members, whilestill allowing some strain to be applied to the bone growth material topromote formation of bone.

[0108] Portions of material may be removed in a desired pattern from aconnector blank so that the connector formed from the blank will havedesired flexibility characteristics. Ends of the blank may be formed sothat the ends couple to implant members. FIG. 7 depicts an embodiment ofconnector 14 having an “X” style of pattern that allows for compressionof flexible member 54. Other patterns may also be used. Openings in thepattern of the connectors may be sufficiently small to inhibit bonegraft from passing through the openings when the connectors form part ofan assembled implant. Flexible members 54 may be formed using a varietyof methods including, but not limited to, milling, drilling, lasercutting, electron discharge machining, and/or masking and etching.

[0109] Connectors 14 and implant members may function together toinhibit fracture of adjacent vertebrae by distributing large forcesapplied to the vertebrae throughout a large contact area between theimplant members and the vertebrae.

[0110] As depicted in FIG. 1 and FIG. 2, connectors 14 may establish aseparation distance between outer surfaces 22 of implant members 12 whenthe connectors are inserted into the tapered slots 32 of the implantmembers. A plurality of connectors 14 that establish various separationdistances between implant members 12 may be included in aninstrumentation set provided to a surgical team that will perform animplant insertion procedure. The availability of several differentconnector sizes may allow formation of implant 10 in a patient that willestablish a desired separation distance between adjacent vertebrae.

[0111] In an embodiment of an instrumentation set, connectors 14 may beprovided that are capable of forming implants 10 having maximumseparation distances between outer surfaces 22 ranging from about 8 mmto about 26 mm in approximately 2 mm increments. Inserting connectors 14of proper size between implant members 12 may form appropriately sizedimplant 10. Connectors 14 may be color-coded and/or include numericalindicia that inform a user of the size of implant 10 that will be formedby the connectors. For example, connector 14 that forms implant 10having a maximum separation of about 12 mm between outer surfaces 22 ofimplant members 12 may be blue and/or include an etched, printed, orstamped “12” on a portion of the connector. Similarly, connector 14 thatforms implant 10 having a maximum separation of about 14 mm betweenouter surfaces 22 of implant members 12 may be green and/or include anetched, printed, or stamped “14” on a portion of the connector.Connector 14 may also include indicia that indicate the size of implantmember 12 that the connector is to be used with. For example, connector14 may include an etched, stamped, or printed “S”, “M”, or “L” on aportion of the connector to indicate a connector that is to be used withsmall, medium, or large implant members 12.

[0112] An optional backing plate may be positioned proximate theposterior side of an assembled implant. FIG. 8 depicts an embodiment ofoptional backing plate 60. Backing plate 60 may be made of abiocompatible polymer, such as, but not limited to, polyethylene,polypropylene, or polyvinyl chloride. Alternatively, backing plate 60may be made of a bioabsorbable and/or biodegradable polymer, such as,but not limited to, a polyanhydride, an alpha polyester, and/or apolylactic acid-polyglycolic acid copolymer. Backing plate 60 mayinclude indentions 62. Indentions 62 may allow a single size backingplate to be adapted to fit within implants of different sizes. Acomplete backing plate may fit within a large implant. The ends ofbacking plate 60 may be cut or otherwise separated at indentions 62 sothat the backing plate fits within a smaller implant. An insertion depthof backing plate 60 in an assembled implant may be limited when tabs 64contact end walls 66 of implant members 12 which define a posterior endof recessed surfaces 38. End walls 66 of implant member 12 are depictedin FIG. 5.

[0113] During an implant insertion procedure, a discectomy may beperformed to remove a portion of intervertebral disc 20 to form discspace 16 between vertebrae 18, as shown in FIG. 3. An implant may beformed within disc space 16. A backing plate may be used when aremaining portion of disc 20 is herniated. Opening 68 in backing plate60 (shown in FIG. 8) may be threaded or otherwise releasably affixed toan insertion rod. The insertion rod may allow insertion and positioningof backing plate 60 between the implant members of the implant from aposition above an opening in a patient. The ability to insert andposition backing plate 60 from above the opening in the patient maypromote visibility and ease of insertion of the backing plate into anassembled implant. After insertion, the rod may be unthreaded orotherwise removed from backing plate 60. Backing plate 60 may inhibitmigration of bone growth material from the implant. Backing plate 60 maynot be necessary if the remaining portion of the disc after thediscectomy is not herniated or otherwise breached.

[0114] FIGS. 9-55 show embodiments of instruments that may be used toform an implant in a patient during a fusion procedure. The instrumentsused during formation of the implant may include, but are not limitedto, width and depth spacers 100, height spacers 200, separators 300,spreaders 400, locking pins 500, extender 600, mallet 650, forceps 700,depth gauges 800, slap hammer 900, and insertion guides 1000.Additionally, seater 1100 and retainer 1300 may be used to securelyfasten connectors to implant members. Various parts of the instrumentsmay be formed of metal, ceramics, polymers, or combinations thereof. Thematerials used to form the parts of the various instruments may havehigh heat resistance and chemical resistance to withstand sterilizationprocedures.

[0115] Instruments used during a fusion procedure may be provided in aninstrumentation set. The instrumentation set may include components ofan implant to be formed. The instrumentation set may also include otherinstruments such as, but not limited to, various types of rongeurs,various types of curettes, bone awls, and tamps.

[0116]FIG. 9 shows an embodiment of width and depth spacer 100. End 102of width and depth spacer 100 may have a shape that substantiallycorresponds to a size of a front surface of an implant member. Sizes ofwidth and depth spacers corresponding to sizes of implant membersincluded in an instrumentation set may be provided in theinstrumentation set. For example, if the instrumentation set includesmedium and large implant members, the instrumentation set may include afirst width and depth spacer with an end that corresponds to largeimplant members and a second width and depth spacer with an end thatcorresponds to medium implant members. An alternate embodiment of awidth and depth spacer may have a first end that substantiallycorresponds to a first size of implant members and a second end thatsubstantially corresponds to a second size of implant members. Outersurfaces of ends 102 may include indicia to indicate the relative sizeof the ends. The indicia may be printed, etched, or otherwise placed onthe ends.

[0117] During formation of a disc space between adjacent vertebrae,portions of an intervertebral disc may be removed. Width and depthspacer 100, together with radiological images, may be used to determinethe proper width and depth of an opening for a particular size ofimplant member. Similarly, width and depth spacers may be used duringformation of an opening between bone segments that are to be fusedtogether by an implant.

[0118] After formation of a disc space or an opening between bonesegments, a height spacer may be used to determine the size of animplant to be formed. FIG. 10 depicts an embodiment of height spacer200. A surgeon may attach height spacer 200 to a slap hammer. Thesurgeon may place an end of the slap hammer in attachment mount 202 andplace the height spacer at a top of a prepared space formed by adiscectomy. The surgeon may insert height spacer 200 with a forceapplied by impacting a slide of the slap hammer against a lower stop. Ifheight spacer 200 fits easily within the disc space with one or twoimpacts from the slap hammer, or without any impacts from the slaphammer, the height spacer may be too small. A larger height spacer maybe attached to the slap hammer and inserted into the prepared discspace. If height spacer 200 will not fit within the disc space withforce applied from the slap hammer, the height spacer may be too large.A smaller height spacer may be attached to the slap hammer and insertedinto the prepared disc space. If height spacer 200 fits within the discspace after three or four impacts from the slap hammer, the heightspacer may correspond to a properly sized implant. After insertion ofheight spacer 200 within the disc space, the spacer may be removed fromthe disc space by impacting the slap hammer slide against an upper stop.During some insertion procedures, an extender (such as extender 600depicted in FIG. 21) and a mallet may be used to insert height spacersinto a disc space.

[0119]FIGS. 11 and 12 show perspective views of separator embodiments.Separator 300 may include body 302, attachment mount 304, passages 306,stop surfaces 308, tongue 310, and arms 312. Body 302 may includecentral opening 314 that reduces the weight of separator 300. Attachmentmount 304 may allow separator 300 to be coupled to a drive device, suchas a slap hammer. Holes 316 through an upper portion of separator 300may define contact surfaces 318 that engage detents of aninsertion/removal instrument, such as detents 902 of slap hammer 900shown in FIG. 27. Passages 306 through body 302 may be sized to allowconnectors and locking pins 500 (shown in FIG. 20) to pass throughseparator 300. Stop surfaces 308 may limit an insertion depth ofseparator 300 into a spreader. Tongue 310 and arms 312 of separator 300may establish a separation distance between implant members that arecoupled to a spreader, such as the embodiment of spreader 400 depictedin FIG. 14. Separation provided by separator 300 may allow the formationof an implant in a disc space without excess distraction of adjacentvertebrae. Tongue 310 may include spreader contact surfaces 320 thatfacilitate insertion of separator 300 into the spreader. Surfaces 320may be chamfered, rounded, or otherwise machined to facilitate insertionof separator 300 into the spreader. Arms 312 may inhibit rotationalmotion of separator 300 with respect to the spreader during an implantinsertion procedure.

[0120] The separator may establish a separation distance between a pairof implant members coupled to a spreader. A connector or connectors maycouple the implant members together after the separator establishes aproper separation distance. The separator may include grooves or othertypes of guides that direct the connector or connectors to properpositions between the implant members. Some separator embodiments maynot include connector passages through the separator to guide theconnectors to proper positions between the implant members. In someembodiments, the connector or connectors may be inserted between theimplant members without interaction with the separator. For example, aconnector may be attached to forceps. A connector may be properlypositioned between the implant members before being released from theforceps.

[0121] A spreader may be used to position implant members betweenadjacent bone structure, such as vertebrae, and aid in establishingproper distraction. A separator may be inserted into a spreader toestablish a desired separation distance between vertebrae or bonesegments.

[0122]FIG. 13 shows a perspective view of an embodiment of spreader 400.Spreader 400 may include may include handle 402, extension portion 404,body 406, and member holders 408. As shown in FIG. 14, spreader 400 mayalso include spring member 410. FIG. 13 shows a spreader embodiment withmember holders 408 in a spread apart position, as if a separator waspositioned between the member holders. FIG. 14 shows a spreaderembodiment with member holders 408 in an initial position prior toinsertion of a separator between the member holders.

[0123] Handle 402 may be an easily graspable member that allows memberholders 408 to be positioned at desired locations within a disc space.Extension portion 404 may provide a spreader with sufficient length sothat handle 402 extends out of a patient when member holders arepositioned between vertebrae or bone segments during a fusion procedure.Body 406 allows member holders to move laterally relative to each other.

[0124] In some embodiments, such as the embodiments depicted in FIG. 13and FIG. 14, handle 402 may be an integral part of body 406 of spreader400, and member holders 408 may be attached to the body. “Integral part”refers to parts that are formed from one piece of material, or fromseparate pieces that are attached together to inhibit axial androtational movement of the separate pieces relative to each other.

[0125] In an alternate embodiment, handle 402 may be an integral part ofextension member 404 and member holder 408′, as depicted in FIG. 15.Body 406 of spreader 400 may be coupled to second member holder 408″, asdepicted in FIG. 16. First member holder 408′ may be an integral part ofbody 406.

[0126] As shown in FIG. 13 and FIG. 14, body 406 of spreader 400 mayinclude a pair of channel members 412. Sets of holes 414 and slots 416may be formed in channel members 412. Holes 414 may allow first memberholder 408′ to be integrally attached to body 406 of spreader 400. Firstmember holder 408′ may be attached by pins 418 between channel members412 so that the first member holder is an integral part of body 406.Pins 418 may be press-fit through holes 414 of body 406 into firstmember holder 408′. Slots 416 allow second member holder 408″ to beattached by pins 418 between channel members 412. Pins 418 may bepress-fit through slots 416 of body 406 into second member holder 408″.Slots 416 allow second member holder 408″ to move relative to body 406and first member holder 408′ when the second member holder is attachedto the body. Slots 416 may allow second member holder 408″ to movelaterally towards or away from first member holder 408′. Axial movementof first member holder 408′ and second member holder 408″ towards adistal or proximal end of spreader 400 is inhibited.

[0127] As shown in the spreader embodiment depicted in FIG. 16, pins 418may be press-fit through slots 416 in body 406 into member holder 408′.Pins 418 may attach second member holder 408″ to body 406 so that thesecond member holder is able to move laterally relative to first memberholder 408′.

[0128] A separation distance between inner surfaces of channel members412 (depicted in FIG. 13, FIG. 14, and FIG. 16) may be slightly largerthan a width of a separator, such as separator 300 depicted in FIG. 11.The separation distance between channel members 412 may inhibit lateraland rotational movement of a separator positioned within spreader 400.The separation distance between channel members 412 may also promoteproper alignment of connector passages 306 of separator 300 with taperedslots in implant members that are coupled to member holders 408 ofspreader 400.

[0129] Spreader 400 may include depth indicators 420, as depicted inFIG. 13 and FIG. 14. Depth indicators 420 may be, but are not limitedto, slots, shoulders, extensions, depressions, and/or indicia in handle402 and/or extension portion 404 of spreader 400. In alternateembodiments, depth indicators may be positioned at other locations ofspreader 400. Depth indicators 420 may be used in association with adepth gauge, such as depth gauge 800 depicted in FIG. 26, to indicatewhen a connector is inserted to a desired depth within implant members.

[0130] Some spreader embodiments may include indicia 422 located near adistal end of spreader 400. Indicia 422 may be etched, printed, adhered,or otherwise placed on spreader 400. FIG. 13 and FIG. 14 depict indicia422 on member holders 408. Indicia 422 may be a scale that indicatesinsertion depth of implant members attached to implant holders 408between vertebrae or bone segments in a length unit (e.g., millimeters).

[0131]FIG. 17 depicts a perspective view that emphasizes inner surfacesof an embodiment of member holder 408. Member holder 408 may includeopenings 424, shoulders 426, connector guide slots 428, and membermounts 430. FIG. 18 shows a perspective view of a portion of anembodiment of member holder 408 that emphasizes an outer surface of theholder. FIG. 19 shows a side view of a portion of an embodiment ofspreader 400.

[0132] Openings 424 (shown in FIG. 17) may be sized slightly smallerthan ends of pins 418 (shown in FIG. 13). Pins 418 may be press-fit intoopenings 424 to join member holder 408 to body 406 of spreader 400.

[0133] Shoulders 426 of member holder 408 may limit insertion depth of aseparator into a spreader. Stop surface 308 of separator 300 (depictedin FIG. 12) may contact shoulders 426 of member holders 408 when theseparator is inserted into the spreader.

[0134] Connector guide slot 428 (shown in FIG. 17) may have a shapecomplementary to the shape of a portion of an implant connector, such asconnector 14 depicted in FIG. 7. When a separator is fully inserted intoa spreader, the ends of connector passages through the separator mayabut and align with connector guide slots 428 in member holders 408. Aconnector inserted into the connector passage of the separator may passthrough the separator, through connector guide slots 428 of memberholders 408, and into tapered slots of implant members that are coupledto the member holders.

[0135] Separator depth indicia 422 on member holders 408 of a spreader,for example, the spreader shown in FIG. 18, may be hidden from view whena separator is initially positioned between member holders of thespreader. Separator depth indicia 422 may become visible when theseparator is fully inserted in the spreader. The visibility of separatordepth indicia 422 will indicate to a surgeon that the separator is fullyinserted into the spreader. Separator depth indicia 422 may be edges ofthe member holders, indentions, etchings, coloring, and/or other typesof markings. For example, in FIG. 17, surface 434 may be silver andsurface 436 may be gold. When a separator is placed between the memberholders of an assembled spreader, the surgeon will initially only seegold surface 436. When the surgeon inserts the spreader to a properdepth, a portion of silver surface 434 will be visible and will indicateto the surgeon that the separator is inserted to a proper depth in thespreader.

[0136] As depicted in FIG. 18, mount 430 of member holder 408 mayinclude raised surface 438, engagers 440, and slots 442. Raised surface438 may be complementary to recess 38 of implant member 12 so thatmotion of the implant member is inhibited relative to the member holderwhen the implant member is coupled to the member holder. An embodimentof implant member 12 with recess 38 is depicted in FIG. 5. Engagers 440may fit within opening 28 in implant member 12. Opening 28 may be acentral opening within implant member 12. Slots 442 may allow portionsof mount 430 to deflect so that engagers 440 may be press-fit ontoimplant member 12. A plurality of slots 442 that do not extend to an endof member holder 408 may inhibit change in the spring properties ofmember holders 408 adjacent engagers 440 that may be caused by droppingor rough handling of spreader 400. In an alternate member holderembodiment, such as member holder 408 depicted in FIG. 15, mount 430 mayinclude single slot 442 in communication with an end of the memberholder. Single slot 442 may be compressed to allow an opening of animplant member to be press fit onto an engager of the member holder.

[0137] When implant members are press-fit onto member holders 408,tapered slots of the implant members may abut and align with connectorguide slots 428 of the member holders, as depicted in FIG. 17. Aconnector may be able to pass through connector guide slots 428 into thetapered slots of the implant members to connect the implant memberstogether.

[0138] Spreader 400 may include spring member 410. As depicted in FIG.14, spring member 410 may be rigidly attached to extension portion 404.Spring member end 444 may contact second member holder 408″. Springmember 410 may apply a force to second member holder 408″ through end444. The force may push second member holder 408″ towards first memberholder 408′. Without a separator positioned between member holders 408,the spring member may place the member holders in an initial position,as depicted in FIG. 14. When spreader 400 is in the initial position,there may be substantially no separation distance between mounts 430 ofmember holders 408. Inserting a separator between member holders 408 maymove second member holder 408″ away from the initial position.

[0139]FIG. 19 depicts a side view of a portion of a spreader embodiment.Member holders 408 are shown in an initial position. Member holders 408may include sloped surfaces 446. Sloped surfaces 446 may establish aseparation distance between member holders 408 when spring member 410forces member holder 408″ to the initial position. The separationdistance allows a separator to be inserted between member holders 408.Spreader contact surfaces, such as spreader contact surfaces 320 ofseparator 300 depicted in FIG. 11, may contact sloped surfaces 446 ofspreader 400.

[0140] Sloped surfaces 446 may allow a separator to gradually increase aseparation distance between the implant members coupled to memberholders 408 as the separator is inserted between the member holders.Sloped surfaces 446 may allow a large component of force applied to theseparator to be transferred to member holders 408 in a directionsubstantially normal to the insertion direction. The force applied tomember holders 408 may increase the separation distance between themember holders so that implant members coupled to the member holdersestablish a desired separation distance between vertebrae or bonesegments.

[0141]FIG. 20 shows a perspective view of an embodiment of locking pin500. Locking pins 500 may secure implant members to a spreader. Lockingpins 500 may also serve as guides for insertion of a separator betweenmember holders of the spreader. Locking pin 500 may include legs 502that are joined together at a top end of the locking pin. Legs 502 oflocking pin 500 may be inserted through connector guide slots ofspreader member holders and into tapered slots of a pair of implantmembers that are coupled to the spreader. Connector guide slots 428 ofspreader 400 are depicted in FIG. 13. Tapered slots 32 of implant member12 are depicted in FIG. 5.

[0142] End portions of each leg 502 may include wide portions 504,tapered portions 506, and compression slot 508. Wide portions 504 may besized to engage walls of connector guide slots of a spreader. Wideportions 504 may slide into or out of the connector guide slots indirections parallel to a longitudinal axis of the guide slots. Dovetailconnections between wide portions 504 and the guide slots may inhibitremoval of the wide portions from the guide slots in directions that arenot parallel to the longitudinal axis of the guide slots.

[0143] Tapers of tapered portions 506 of locking pins 500 maysubstantially correspond to the taper of implant member tapered slots.Tapered portions 506 may form a dovetail connection with implant membertapered slots that allows removal of the tapered portions from thetapered slots only in a direction opposite to an insertion direction.Insertion of tapered portions 506 into the tapered slots of implantmembers may reduce a separation distance between portions of locking pin500 that define compression slot 508. Reduction of the separationdistance generates a force applied by locking pin legs 502 to theimplant members. The force secures locking pin legs 502 to the implantmembers.

[0144] When locking pin 500 is inserted into a spreader and into implantmembers coupled to the spreader, some of wide portions 504 of each leg502 may be positioned in a tapered slot of an implant member and some ofwide portions 504 of each leg may be positioned in a connector guideslot of the spreader. When implant members are press-fit on memberholders, tapered slots of the implant members may align and abut withconnector guide slots of the spreader. Locking pins 500 may maintain theabutted and aligned positions of the implant members relative to themember holders of the spreader.

[0145] Locking pins 500 may secure implant members to a spreader priorto insertion of the spreader into a patient. The connections between theimplant members, spreader, and locking pins may be visually checkedprior to insertion of the spreader into the patient. A physical check ofthe connections between the implant members, spreader, and locking pins500 may be performed by inserting the locking pins and then turning thespreader upside down. Force applied to the implant members by lockingpins 500 due to reduction of compression slot 508 should be sufficientto hold the locking pins in position even when the spreader is turnedupside down. Locking pins may be removed from the spreader and implantmembers by grasping the locking pins and pulling the locking pins in adirection opposite to an insertion direction.

[0146] A spreader may be positioned between vertebrae or bone segmentsafter locking pins 500 are positioned to securely couple implant membersto the spreader. A separator may then be inserted into the spreader toallow the implant members to distract the vertebrae or bone segments toa desired separation distance. An extender may be attached to theseparator to facilitate placement and insertion of the separator intothe spreader.

[0147] An extender embodiment is depicted in FIG. 21. Extender 600 maybe coupled to a separator, such as separator 300 depicted in FIG. 12.Extender 600 may include end 602, detents 604, shaft 606, and impactsurface 608. A portion of end 602 may fit in attachment mount 304 ofseparator 300. Detents 604 may engage separator surface 318. Internalsprings may extend detents 604 with enough force so that the detentssupport the weight of the separator, but without enough force to makeremoving extender 600 from the separator difficult. A portion of end 602may overlap a portion of a top surface of the separator so that impactforce applied by a mallet or other instrument to impact surface 608 willdrive the separator into the spreader. FIG. 22 depicts an embodiment ofmallet 650 that may be used to insert instruments. Shaft 606 may provideextender 600 with enough length to allow a separator that is attached tothe extender to be manipulated from above an opening in a patient.Manipulating the separator from above the opening may allow for goodvisibility of positioning and placement of the separator.

[0148] Extender 600 may allow a separator to be positioned so thatlocking pins are positioned through passages of the separator and sothat the spreader contact surfaces of the separator contact slopedsurfaces of the spreader. An impact instrument, such as a mallet, mayapply force to impact surface 608 that drives the separator into thespreader until the stop surface of the separator contacts shoulders ofthe member holders. After the separator is inserted into the spreader,extender 600 may be removed from the separator by holding the separatorin position and pulling the extender upwards. During some procedures, aslap hammer or other device may be used to insert the separator into thespreader. When the separator is driven into the spreader, implantmembers connected to the spreader are separated a desired separationdistance. Driving the separator into the spreader may drive protrusionsof the implant members into adjacent bone.

[0149]FIG. 23 depicts a representation of locking pins 500 positioned intapered slots 32 of implant member 12 that is press-fit onto a spreader.Locking pins 500 extend through separator 300. Tongue 310, arms 312, andcentral opening 314 of separator 300 are shown in cross section.

[0150] After separator 300 is fully inserted into a spreader, lockingpins 500 may be removed from the separator by grasping the locking pinsand pulling the locking pins in a direction opposite to an insertiondirection.

[0151] Connectors may be inserted through connector passages 306 ofseparator 300 (shown in FIG. 12), through guide slots 428 of spreader400 (shown in FIG. 13), and into tapered slots of implant memberspress-fit onto the spreader. FIG. 24 depicts a partial representation ofseparator 300 inserted into spreader 400 with connector 14 positioned tobe released into connector passage 306 of the separator. Connector 14may be attached to forceps 700 and dropped into connector passages 306of separator 300. Grasping ends 702 of forceps 700 may accept a wide endof connector 14, but not a narrow end of the connector. When forceps 700are fully closed, a narrow end of connector 14 may not be held by ends702 of the forceps. The ability to grasp the wide end of connector 14with the forceps, but not the narrow end, may ensure that connectors arein a proper orientation before being released into connector passages306 of separator 300.

[0152]FIG. 25 depicts a representation of connectors 14 positioned intapered slots 32 of implant members 12 that are press-fit onto aspreader. After insertion of connectors 14 into tapered slots 32 ofimplant members, a depth gauge may be used to drive the connectors to adesired depth within the tapered slots of implant members. Connectorpassages 306, tongue 310, arms 312, and central opening 314 of separator300 are shown in cross section.

[0153]FIG. 26 depicts an embodiment of depth gauge 800 that may be usedto drive connectors to proper depths within tapered slots of implantmembers. End 802 may be placed through connector passages of a separatorto contact connectors positioned between implant members. Depth gauge800 may be driven downwards until handle 804 interacts with a depthindicator of a spreader, such as depth indicator 420 of spreader 400depicted in FIG. 13. Depth gauge 800 may be used on each connector toensure that the connectors are inserted to the proper depth. Handpressure against handle 804 should be sufficient to drive a connector tothe proper depth between implant members. If needed, an impactinstrument may be tapped against handle 804 to insert a connector to theproper depth.

[0154] After insertion of the connectors, a separator may be removedfrom a spreader. A slap hammer may be attached to an attachment mount ofthe separator. The slap hammer may be used to remove the separator fromthe spreader.

[0155]FIG. 27 depicts an embodiment of slap hammer 900 that may be usedto remove a separator from a spreader. Slap hammer 900 may includedetents 902, insertion portion 904, shaft 906, slide 908, upper stop910, and activator 912. Insertion portion 904 may fit within anattachment mount of a separator, such as attachment mount 304 ofseparator 300 depicted in FIG. 12. Activator 912 may be pulled towardsslide 908 to allow detents 902 to move inward within insertion portion904 so that the insertion portion may be placed in the attachment mountof the separator. After placement of insertion portion 904 in theseparator attachment mount, activator 912 may be released to extenddetents 902 out of insertion portion 904 and affix slap hammer 900 tothe separator. Slide 908 may be grasped and repeatedly impacted againstupper stop 910 to remove the separator from the spreader. In addition toremoving a separator from a spreader, slap hammer 900 may be used toinsert a separator into a spreader. In some embodiments, slap hammer 900may be used to position, insert, and/or remove other instruments thathave attachment mounts that are complementary to insertion portion 904of the slap hammer.

[0156]FIG. 28 depicts a cross-sectional representation of a slap hammerembodiment that has cylindrical detents 902. Cylindrical detents mayprovide a large contact surface for engaging an instrument attached tothe slap hammer. In other embodiments, detents may be spherical,hemispherical, or have other shapes., Slap hammer 900 is depicted in aposition where activator 912 is pulled away from end 914 of the slaphammer so that spring 916 is compressed against spring stop 918 of shaft906. Rod 920 is drawn up in shaft 906 so that end 922 of the rod doesnot engage detents 902. Detent slots 924 may be placed over pins 926.Slots 924 allow detents 902 to move into or out of insertion portion904. When activator 912 is pulled up, as depicted in FIG. 28, detents902 are free to move within insertion portion 904, and slap hammer 900may be placed in or be removed from an attachment mount of aninstrument. When activator 912 is released, spring 916 will uncompressand force rod 920 towards end 914 of slap hammer 900. Rod 920 maycontact detents 902 and force the detents to extend outside of insertionportion 904. When activator 912 is released so that spring 916 extendsrod 920 such that the rod is adjacent to detents 902, the rod willinhibit movement of the detents relative to insertion portion 904.

[0157] After removal of a separator from a spreader, the spreader may bedisengaged from implant members. Twisting the spreader relative to theimplant members may release the press-fit connection between the implantmembers and the spreader. The spreader may then be removed from thepatient. Implant members that are joined together by connectors may beleft in a disc space between vertebrae or within an opening between bonesegments. A connector seater may subsequently be used to affix theconnectors to the implant members.

[0158]FIG. 29 depicts a perspective view of a portion of an embodimentof slap hammer 900. Slap hammer 900 may include end connector 928. Endconnector 928 may include slot 930 and holder 932. A rod in a spreader,or other instrument that is to be used with slap hammer 900, may fit inslot 930. Slap hammer 900 may be rotated about 90° to place the bar inholder 932. Slide 908 may be grasped and repeatedly impacted against anupper stop 910 during use of slap hammer 900.

[0159]FIG. 30 and FIG. 31 show various views of embodiments ofseparators 300. Separator 300 with body 302 may include tongue 310, arms312, central openings 314, and groove 322 for aligning separator 300with a spreader, such as spreader 400 depicted in FIG. 36. Groove 322may guide separator 300 between implant members attached to memberholders of spreader 400 during a spinal fusion procedure. Separator 300may include impact surface 324. Separator 300 may include indention 326for coupling to spreader retention mechanisms. Indention 326 may beconfigured to accept a portion of a spreader retention mechanism toinhibit movement of separator 300 when the separator is inserted intospreader 400. Indention 326 may be an opening through separator 300. Theopening may intersect attachment mount 304. Detents of an impactinstrument, such as a slap hammer, may engage a surface that defines theopening to couple the impact instrument to separator 300.

[0160] During a fusion procedure, a mallet (such as mallet 650 depictedin FIG. 22) or other impact instrument may be used to insert a separatorinto a spreader positioned between vertebrae or bone segments that areto be fused together. Impact surface 324 of separator 300 may beimpacted to drive the separator into a spreader, such as spreader 400depicted in FIG. 36. A slap hammer may be used to remove separator 300and other insertion instruments from a patient. The slap hammer may beconnected to attachment mount 304 prior to use.

[0161] As depicted in FIG. 31, connector passage 306 may have a shapethat substantially corresponds to a shape of a connector. A properlysized connector may slide through connector passage 306. A wide end of aconnector (e.g., connector 14 shown in FIG. 7) may be colorcoded and/orinclude indicia that inform a user which end of the connector is thewide end. During insertion of connector 14 into connector passage 306 ofseparator 300 (shown in FIG. 30 and FIG. 31), the color-code or indiciamay inform a user if the connector is oriented in the proper direction.For example, the wide end of a connector may be stamped with a “W”. Ifthe “W” is visible prior to the connector being released into passage306, the user will know that the connector is being inserted in theproper orientation. In some embodiments, a narrow end of connector 14may be color-coded and/or include indicia that informs a user that theconnector is about to be inserted improperly. For example, the narrowend of a connector may be color-coded red. If the red color is visibleprior to the connector being released into passage 306, the user willknow not to release the connector into the passage.

[0162] Connector passages 306 through a separator may be adapted toaccommodate a specific size of connector. For example, passage 306 maybe sized to allow a connector that will form an implant with about a 12mm separation distance between outer surfaces of implant members to passthrough the separator. An instrumentation set for an implant fusionprocedure may include a separator for each implant member size includedin the instrumentation set. The separators may have connector passages306 of different sizes to allow for formation of implants havingdifferent heights. For example, an instrumentation set may includeseparators for forming implants ranging in size from about 8 mm implantsto about 24 mm implants in approximately 2 mm increments. Connectors foreach size of separator may also be supplied with the instrumentationset.

[0163]FIG. 32 depicts an embodiment of depth gauge 800 that may be usedwith separator 300 depicted in FIG. 30. Depth gauge 800 may includeshaft 806 that fits within connector passages 306 of separator 300.Depth gauge handle 804 may be larger than connector passages 306. Depthgauge handle 804 may engage shoulders of a spreader that the separatoris inserted into. Connectors may be inserted into connector passages ofthe separator when the separator is positioned between member holdersand implant members coupled to the member holders. Depth gauges 800 maybe placed in the connector passages to push the connectors to properdepths within tapered slots in the implant members. The depth gauges maybe pushed and/or impacted into the separator until depth gauge handles804 contact the spreader and/or separator. After insertion, thespreader, separator, and depth gauges may be removed as a unit from theimplant members by a slap hammer or other removal instrument.

[0164]FIG. 33 depicts another embodiment of separator 300. Body 302 ofthe separator may have side openings 328 into passages 306 proximatedistal ends of arms 312. Assembled connectors 14 may be inserted, orpreloaded, into side openings 328 prior to inserting separator 300 intospreader 400 (e.g., the spreader depicted in FIG. 14). Side openings 328may have shapes that only allow for insertion of connectors 14 whennarrow ends of the connectors are facing a distal end of separator 300and wide ends of the connectors are facing a proximal end of theseparator. The shape of side openings 328 may prevent backward insertionof connectors 14 into separator 300. A pair of spring loaded detentspositioned and sealed in detent openings 330 on sides of each sideopening 328 may inhibit undesired release of connectors 14 from the sideopenings.

[0165] Separator 300 may include depth gauge passages 332 through theseparator from a proximal end of the separator to side openings 328.Below side openings 328, separator 300 may have connector passages 306sized to allow connectors to pass from the separator to implant members.Depth gauges may be inserted into depth gauge passages 332. When thedepth gauges are inserted into passages 332, the depth gauges may pushconnectors 14 positioned in side openings 328 past detents in the sideopenings so that the connectors are pushed into connector passages 306.Connectors 14 may pass from connector passages 306 into tapered slots ofimplant members during formation of an implant.

[0166]FIG. 34 depicts an embodiment of depth gauge 800 that may be usedwith the separator embodiment depicted in FIG. 33. Depth gauge 800 mayinclude shaft 806. In an embodiment, shaft 806 may be a cylindricalshaft. In other embodiments, the shaft may have a different geometricalshape. Passages 332 in separator 300 may be sized and shaped to allowshaft 806 to pass through the passage so that end 802 contacts aconnector positioned in side opening 328. In an embodiment, passage 332may be a cylindrical passage. Forming a cylindrical passage may beeasier and less expensive than forming a passage having a differentgeometric shape.

[0167] End 802 of depth gauge 800 may dislodge a connector from a sideopening so that the connector passes into a connector passage of theseparator. Depth gauge 800 may have sufficient length so that end 802pushes the connector to a desired depth in implant members coupled to aspreader when the depth gauge is fully inserted into the separator.Depth gauge handle 804 may fit within a recess if fully inserted intothe separator. Recess 334 for depth gauge handle 804 is shown in FIG.33. If needed, a mallet or other impact surface may be used against atop surface of handle 804 to drive the depth gauge into the separator.

[0168] In a separator embodiment, such as separator 300 depicted in FIG.33, first member 336 of the separator may be a separate piece fromsecond member 338. Second member 338 may be releasably attached to firstmember 336. Detents 340 in first member 336 may interact with openings342 in second member 338 to join the first member to the second member.Simultaneously depressing detents 340 may allow first member 336 to beseparated from second member 338. Other fastening systems may be used tojoin a first member to a second member. A single first member 336 may beprovided in an instrumentation set for a spinal fusion: procedure.Various second members 338 for each size of connector provided in theinstrumentation set may be provided in the instrumentation set. Havingfirst member 336 separable from second member 338 may allow forreduction of weight of an instrumentation set and may increase availablespace within an enclosure that houses the contents of theinstrumentation set.

[0169] Separator body 302 may include ridge 344. Ridge 344 may be a stopsurface that limits insertion depth of separator 300 into a spreader.

[0170]FIG. 35 depicts a portion of an embodiment of separator 300 thatmay be removed from a patient using the slap hammer embodiment depictedin FIG. 29. Separator 300 may include bar 346. Bar 346 may be press fit,threaded, welded, or otherwise attached to body 302 of separator 300.During removal of separator from a patient, bar 346 may fit within aslot of the slap hammer. When the slap hammer is rotated about 90°, bar346 may fit within a holder of the slap hammer.

[0171]FIG. 36 depicts an embodiment of spreader 400 in an initialposition. Member holders 408 of spreader 400 may be sized so that widthsof the member holders are smaller than widths of grooves in a separator(e.g., grooves 322 in separator 300 depicted in FIG. 30). The separatormay slide down member holders 408 when the separator is inserted intospreader 400. Spreader body 406 may include opening 448 for theinsertion of the separator. Member holders 408 may be positionedopposite each other on opposing sides of opening 448 to allow aseparator to be positioned between member holders 408. When in theinitial position, there may be substantially no separation distancebetween member mounts 430.

[0172] Body 406 may include shoulder 450 on sides of opening 448.Shoulder 450 may engage a separator ridge (e.g., ridge 344 of separator300 depicted in FIG. 33). Body 406 may include retainers 452. In someembodiments, a spreader may only include one retainer. Retainer 452 mayinclude engager 454. Each retainer 452 may be coupled to body 406 abouta pivot axis by a spring. The spring may be a torsion spring. The springmay bias engager 454 towards opening 448. Engager 454 may be pushedoutwards when a separator is inserted into spreader 400. The spring mayforce engager 454 towards the separator. Engager 454 may enter anopening in the separator (e.g., indention 326 in separator 300 depictedin FIG. 30) when the separator is fully inserted into spreader 400. Whenengager 454 is positioned in the opening of the separator, the separatorand spreader 400 are linked together.

[0173] In an alternate embodiment, a retainer of a spreader may notinclude a spring member. An interference fit may be formed between aportion of the retainer and a portion of the spreader when the retaineris in a closed position such that the retainer holds an instrumentwithin the spreader. The retainer may be rotatively coupled to thespreader about an axis. A rotational range of motion may be limited. Inan embodiment, the rotational range of motion is limited to less than45°. The retainer may be manually released and attached to a body of thespreader by contacting the retainer and rotating the retainer away ortowards the spreader. The retainer may include a textured contactsurface to facilitate rotating the retainer.

[0174] Retainer engagers 454 may include chamfered surfaces that promoterotation of retainers 452 away from a body of a separator when aninstrument, such as a separator, is inserted into opening 448. Thechamfered surfaces allow initial deflection of retainers 452 when theseparator is inserted into spreader 400 so that a user does not have tomanually pull the retainers outwards.

[0175] Retainer 452 may include contact surface 456. Pushing contactsurface 456 may rotate retainer 452 about a pivot axis and allow engager454 to be removed from an opening in a separator that is fully insertedinto spreader 400. The separator may be removed from spreader 400 whencontact surfaces 456 of retainers 452 are depressed and the separator ispulled away from the spreader.

[0176]FIG. 37 depicts an embodiment of member mounts 430 of memberholders 408. Member holders 408 may include sloped surfaces 458, springmembers 460, and stops 462. Sloped surfaces 458 may form a dovetailconnection with sloped surfaces of implant members (e.g., slopedsurfaces 70 of implant member 12 depicted in FIG. 2). When an implantmember is coupled to member holder 408, spring member 460 may provide aforce against the implant member that holds the implant member to themember holder. Stop 462 may limit insertion of the implant onto memberholder 408. In some spreader embodiments, spring member 460 and stop 462may be integral members.

[0177] A distance between sloped surfaces of implant members, such assloped surfaces 70 of implant members 12 depicted in FIG. 2, may varydepending on the size of the implant members. A spreader that has memberholders that mate with sloped surfaces of implant members may beprovided for each size of implant member included in the instrumentationset. For example, if the instrumentation set includes medium and largeimplant members, the instrumentation set will include a first spreaderwith member holders sized to accept the medium sized implant members anda second spreader with member holders sized to accept the large sizedimplant members.

[0178] To prepare a spreader for a fusion procedure, implant members maybe inserted onto member holders of the spreader. A visual check may beperformed to check that the implant members are fully inserted onto themember holders so that end surfaces of the implant members contact stopsof the spreader. The implant members may be inserted into a disc spacebetween vertebrae or into an opening between bone segments. In someembodiments, a disc space or an opening between bone segments is largeenough to accept the implant members. In some embodiments, a disc spaceor an opening between bone segments may be too small to allow forinsertion of implant members. If the disc space or opening is too small,an end cap may be placed on the spreader, and impact forces may beapplied to the spreader to insert the implant members into the discspace or into the opening between bone segments. Insertion guides may beused to inhibit protrusions of the implant members from scarringsurfaces of vertebrae or bone segments.

[0179]FIG. 38 depicts an embodiment of member mounts 430 of memberholders 408. Member holders may include sloped surfaces 458, arms 464,and slot 466. Sloped surfaces 458 may form a dovetail connection withsloped surfaces of implant members (e.g., sloped surfaces 70 of implantmember 12 depicted in FIG. 2). Arms 464 may include a slight taper. Thetaper may limit an insertion depth of an implant member onto membermount 430. When an implant member is coupled to member holder 408, thetaper of arms 464 may cause compression of slot 466. Compression of slot466 may cause arms 464 to apply a force to the implant member that holdsthe implant member onto the member mounts 430.

[0180]FIG. 39 depicts an embodiment of end cap 468 for a spreader. Endcap 468 may be placed in an opening in a body of a spreader (e.g.,opening 448 of spreader 400 depicted in FIG. 36). Impact end cap 468 mayinclude upper surface 470, ridge 472, openings 474, and lower body 476.Lower body 476 of impact end cap 468 may be shaped and sized to fitwithin opening 448 of spreader 400 depicted in FIG. 36. Engagers 454 mayextend into openings 474 when end cap 468 is inserted into the spreader.Ridges 472 of impact end cap 468 may contact shoulders 450 of spreaderbody to provide a large contact surface between end cap 468 and spreader400.

[0181] If implant members attached to ends of member holders are toothick to allow for insertion into a prepared disc space, an insertionguide and an impaction instrument may be used to insert the implantmembers into the disc space. FIG. 40 depicts an embodiment of insertionguide 1000. Insertion guide 1000 may be inserted into a disc space or aspace between bone segments until stop 1002 contacts bone. Stop 1002 mayextend across a back surface of insertion guide 1000. In someembodiments, insertion guides may not include stops. Insertion guides1000 may be made of thin metal strips. The metal may have a hardnessequal to or greater than a hardness of protrusions extending fromimplant members so that the protrusions will not significantly score theinsertion guides. In other embodiments, insertion guides may be made ofpolymer, or include a polymer coating, that is able to resist scoringfrom protrusions of implant members. In some embodiments, a singleinsertion guide may include two strips. The insertion guide may bepositioned between vertebrae or bone structures. Implant membersattached to a spreader may be inserted between the two strips of theinsertion guide.

[0182]FIG. 41-44 depict embodiments of insertion guide 1000. FIG. 41depicts an embodiment of joined together insertion guide 1000. Insertionguide 1000 may include first arm 1004, second arm 1006, and cap 1008.End portions of first arm 1004 and second arm 1006 may be inserted in adisc space formed between vertebrae. Portions of first arm 1004 andsecond arm 1006 may extend into cap 1008. Cap 1008 may be separated fromfirst arm 1004 and second arm 1006 to allow for separation of the firstarm and the second arm. As shown in FIG. 42, cap 1008 may include shaft1010. Cap 1008 and shaft 1010 may help keep first arm 1004 and secondarm 1006 joined together before and during insertion of end portions ofinsertion guide 1000 into the disc space. After end portions areinserted into the disc space, cap 1008 and shaft 1010 may be removedfrom first arm 1004 and second arm 1006 to allow for separation of thefirst arm and the second arm.

[0183] After placement of insertion guide 1000 and removal of cap 1008and shaft 1010, a spreader with attached implant members may be insertedbetween first arm 1004 and second arm 1006. The implant members may beinserted into a disc space. FIG. 43 depicts a spreader with attachedimplant members positioned between first arm 1004 and second arm 1006.After insertion of implant members into the disc space, first arm 1004and second arm 1006 may be removed. FIG. 44 depicts the spreader andimplant members after removal of first arm 1004 and second arm 1006.

[0184]FIG. 45 depicts a spreader and end cap combination. Afterplacement of the insertion guides on each side of a disc space or anopening between bone segments, implant members 12 coupled to spreader400 may be positioned between the insertion guides. A mallet or otherimpact instrument may strike upper surface 470 of end cap 468 to drivespreader 400 into the disc space or between the bone segments. Afterimplant members 12 are inserted to a desired depth, insertion guides maybe removed, and impact end cap 468 may be released and removed fromspreader 400.

[0185] After insertion of implant members that are connected to aspreader into a disc space or opening between bone segments, a separatormay be inserted into the spreader. A separator, such as separator 300depicted in FIG. 33, may be placed in an opening of a spreader, such asopening 448 in spreader 400 depicted in FIG. 36. An impact instrumentmay be used to force the separator between member holders 408 ofspreader 400. Sloped surfaces of member holders 408 and chamfered endsurfaces of the separator may allow a large portion of the force appliedto the separator to separate implant members coupled to the spreader.The implant members may establish a desired separation distance betweenvertebrae or bone segments without overdistracting the vertebrae or bonesegments. Protrusions of the implant members extend into adjacent boneto anchor the implant members to bone. When the separator is fullyinserted into the spreader, engagers of the spreader may enter intoopenings of the separator to join the separator and the spreadertogether.

[0186] After insertion of the separator into the spreader, depth gaugesmay be inserted into the depth gauge passages of the separator. Ifneeded, an impact instrument may be used to tap handles of the depthgauges to force the depth gauges into depth gauge recesses in theseparator. Pushing the depth gauges into the separator may releaseconnectors positioned in the spreader into connector passages. Placingdepth gauge handles in the separator recesses positions the connectorsin tapered slots in implant members connected to the spreader.

[0187] After insertion of the depth gauges, a slap hammer may beattached to the separator. FIG. 46 depicts an embodiment of slap hammer900 coupled to separator 300. In some embodiments, the slap hammer mayinclude detents that connect to an engagement surface of the separator.In other embodiments, an attachment mount of the separator may bethreaded, and an end of the slap hammer would include mating threadingthat allows the slap hammer to be joined to the separator.

[0188] After joining slap hammer 900 to separator 300, slide 908 may beimpacted against upper stop 910. The impaction removes separator 300,spreader 400, and depth gauges 800 from implant members 12 that aresecured to bone by protrusions of the implant members. Removingseparator 300, spreader 400, and depth gauges 800 leaves implant members12 and connectors in the disc space or in the space between bonesegments. Separator 300, spreader 400, and depth gauges 800 may beseparated from each other when convenient.

[0189] Implant members that are joined together by connectors may beleft in a disc space between vertebrae or within an opening between bonesegments after removal of separator 300, spreader 400, and depth gauges800. A connector seater may subsequently be used to affix the connectorsto the implant members.

[0190] A seater may be used to permanently affix connectors to implantmembers after an implant has been formed in a patient. Seater 1100 mayapply force to the connectors and implant members to drive theconnectors into tapered slots of implant members. Forces applied to theconnectors and implant members may be sufficiently large to deform theslots and/or connectors so that the connectors cannot be removed fromthe implant members.

[0191]FIG. 47 depicts an embodiment of seater 1100. Seater 1100 mayinclude attachment portion 1102, extender 1104, and activation mechanism1106. Threaded connections, quick disconnect connections, or other typesof connections may couple attachment portion 1102 to extender 1104, andthe extender to activation mechanism 1106. In some embodiments,attachment portion 1102, extender 1104, and/or activation mechanism 1106may be permanently coupled together by welds or sealant. In otherembodiments, attachment portion 1102, extender 1104, and/or activationmechanism 1106 may be formed as a single inseparable unit. Seater 1100may include openings 1108. Openings 1108 may allow steam and/or otherdisinfectants to enter into seater 1100 during a sterilizationprocedure.

[0192] Attachment portion 1102 of a seater may include drive rod 1110,connector engager 1112, and member engager 1114, as shown in FIGS. 47and 48. A spring in attachment portion 1102 may hold drive rod 1110 inan initial position. Engaging an activation mechanism of seater 1100 mayextend drive rod 1110 to a second position. The spring may return driverod 1110 to the initial position when activation mechanism 1106 isdisengaged. Drive rod 1110 may be coupled to connector engager 1112.When member engager 1114 is coupled to an implant member, engagingactivation mechanism 1106 of seater 1100 may extend drive rod 1110 andconnector engager 1112 coupled to the drive rod relative to stationarymember engager 1114. Ends 1116 of connector engager 1112 may be forcedagainst connectors to drive the connectors into the tapered slots in theimplant members.

[0193] Connector engager 1112 of seater 1100 may have ends 1116 thatpress against the connectors positioned within implant members.Connector engager 1112 may be sized to contact the connectors that arespaced a set distance apart in a specific size of implant member.Connector engager 1112 for each implant member size may be included inan instrumentation set that is provided to a surgical team that willperform an implant insertion procedure. For example, an instrumentationset may include a small, medium, and/or large connector engager 1112.Connector engager 1112 may be positioned within a slot in an end ofdrive rod 1110 of the seater. Fastener 1118 may attach connector engager1112 to drive rod 1110. In an embodiment, fastener 1118 is a screw. Inother embodiments, other types of fasteners 1118 may be used, orconnector engager 1112 may be permanently attached to drive rod 1110 ofattachment portion 1102 of a seater.

[0194] As shown in FIG. 48, member engager 1114 may include extensions1120. Extensions 1120 may be placed within openings 28 in implant member12 (depicted in FIG. 1). Extensions 1120 may be positioned againstrecessed surfaces 30 of implant member 12 to couple seater 1100 to theimplant member.

[0195] A retainer may be used to inhibit unintentional removal of seater1100 (shown in FIG. 47) from implant member 12 (shown in FIG. 1). FIG.49 depicts an embodiment of retainer 1300. Retainer 1300 may includehandle 1302 and spacer 1304. Handle 1302 may allow for easy positioningof spacer 1304. Spacer 1304 may be placed between a first implant memberthat is not coupled to a seater and a seater that is coupled to a secondimplant member. Spacer 1304 may inhibit disengagement of extensions 1120of attachment portion 1102 of seater 1100 (shown in FIG. 48) from thesecond implant member during use of the seater.

[0196] Another embodiment of retainer 1300 with handle 1302 is shown inFIG. 50. Spacer 1304 may be placed between a seater coupled to animplant member and an implant member that is not coupled to the seater.Spacer 1304 may include stop surface 1306. Stop surface 1306 may limitan insertion depth of retainer 1300 between implant members. Spacer 1304may inhibit disengagement of the attachment portion of the seater froman implant member during use of the seater.

[0197]FIG. 51 depicts a cross-sectional representation of a seaterembodiment. Extender 1104 of seater 1100 may include internal drive rod1122 and outer body 1124. Spring 1126 within extender 1104 may forcedrive rod 1122 to an initial position. Engaging activation mechanism1106 of seater 1100 may force drive rod 1122 towards attachment portion1102 coupled to extender 1104. Extender 1104 may provide a length toseater 1100 that allows a surgeon to easily attach the seater to animplant member within a patient. The length of seater 1100 may allow thesurgeon to activate the seater to couple connectors to the implantmember from above an opening in the patient.

[0198]FIGS. 51 and 52 show cross-sectional views of an embodiment ofactivation mechanism 1106 of a seater. Activation mechanism 1106 mayinclude body 1128, handle 1130, first drive rod 1132, second drive rod1134, return spring 1136, drive plate 1138, set shaft 1140, washersprings 1142, button housing 1144, button latch 1146, button spring1148, button 1150, and end cap 1152. Body 1128 may include first slot1154 and second slot 1156 (as depicted in FIG. 47). First drive rod 1132and return spring 1136 may be positioned within body 1128 of activationmechanism 1106. Handle 1130 may be coupled by pin 1158 to first slot1154 (shown in FIG. 47) of body 1128 so that an end of the handlecontacts an end of first drive rod 1132 (shown in FIG. 48). Second driverod 1134 may be pivotally coupled to handle 1130 near a first end ofsecond drive rod 1134 and pinned to second slot 1156 of body 1128 (shownin FIG. 51) near a second end of the second drive rod.

[0199] When handle 1130 is squeezed so that the handle moves from aninitial position towards body 1128, end 1160 of the handle may contactend 1162 of first drive rod 1132 (shown in FIG. 51). The contact mayextend first drive rod 1132 towards extender 1104 coupled to body 1128.End 1162 of first drive rod 1132 may contact and extend drive rod 1122within extender 1104. Drive rod 1122 of extender 1104 may contact andextend drive rod 1110 of attachment portion 1102 of seater 1100. Returnspring 1136 may return first drive rod 1132 to an initial position whenhandle 1130 is returned to an initial position. Similarly, returnsprings in attachment portion 1102 and extender 1126 may return driverod 1110 in the attachment portion and drive rod 1122 of the extender toinitial positions when the handle returns to an initial position.Connector engager 1112 may be coupled to drive rod 1110.

[0200] As depicted in FIG. 52, set shaft 1140 of a seater may threadinto drive plate 1138. Drive plate 1138 may include spring supportsurface 1164 and spring support extension 1166. Set shaft 1140 may bethreaded into spring support extension 1166 of drive plate 1138. Setshaft 1140 and drive plate 1138 may have ultrafine threading that allowsfor precise adjustment of a length of the set shaft that extends beyondtop surface 1168 of the drive plate. A setscrew may be threaded intodrive plate 1138 against an unthreaded portion of set shaft 1140. An endof the setscrew may press against set shaft 1140 to inhibit unwantedmovement of the set shaft after the set shaft has been set to a desiredposition. Set shaft 1140 may include a drive tool slot that mates to adrive tool that rotates the set shaft. The drive tool may be a hexwrench, screwdriver, or other type of drive tool. The position of setshaft 1140 may be adjusted during calibration of the seater.

[0201] The position of set shaft 1140 may determine the amount of forcethat second drive rod 1134 needs to apply to drive plate 1138 to causebutton 1150 to pop up through end cap 1152 (shown in FIG. 51 and FIG.52). The amount of force needed to cause button 1150 to pop up throughend cap 1152 may be substantially the same as the amount of forceapplied to an object that contacts the end of the first drive rod. Assuch, button 1150 may serve as an indicator when sufficient force isapplied through the seater to the implant. Enough force may be appliedto the connectors and an implant member to permanently lock and affixthe connectors to the implant member as indicated when button 1150 popsup through end cap 1152.

[0202] Belleville or conical washer springs 1142 may be placed overspring support extension 1166 and against spring support surface 1164 ofdrive plate 1138. Springs 1142 may include convex and concave sides. Theconvex and concave sides of springs 1142 may allow a stacked set ofsprings to axially compress or expand depending on a load applied to atop and bottom of a spring stack. In an embodiment of activationmechanism 1106, a convex side of first washer spring 1142 may be placedover spring support extension 1166 and against spring support surface1164 of drive plate 1138. A concave side of second washer spring 1142may then be placed over spring support extension 1166 and against thefirst washer spring. Remaining washer springs 1142 may be placed aroundset shaft 1140 in an alternating convex-concave pattern. In anembodiment, six washer springs 1142 are used. In other embodiments,fewer or more washer springs 1142 may be used. The convex-concavepattern allows for compression of washer springs 1142 during use so thatend 1170 of set shaft 1140 may activate button trigger 1146 of theseater.

[0203] Assembled drive plate 1138, set shaft 1140, and set of washersprings 1142 may be placed in seater body 1128 against an end of seconddrive shaft 1134. Alternately, drive plate 1138, set shaft 1140, and setof washer springs 1142 may be individually positioned within the bodyagainst the end of second drive shaft 1134.

[0204]FIG. 52 shows a detailed view of an embodiment of an end ofactivation mechanism 1106. Button 1150, button spring 1148, and buttonlatch 1146 may be coupled to button housing 1144. Button housing 1144may be placed on top of washer springs 1142, and end cap 1152 may bethreaded onto body 1128 to form assembled activation mechanism 1106.Button 1150 and button latch 1146 may have through openings that allow adrive tool to be inserted into set shaft 1140 of assembled activationmechanism 1106. A height that set shaft 1140 extends above drive plate1138 may be adjusted with the drive tool without disassemblingactivation mechanism 1106.

[0205] Button latch 1146 may include arm 1172 and hook 1174 that engagessurface 1176 of button 1150. Button latch 1146 may be pivotally coupledto button housing 1144. When the handle of activation mechanism 1106moves towards body 1128 and a force is applied by end 1162 of firstdrive rod 1132 to an object, second drive rod 1134 applies an oppositeforce to drive plate 1138. The force applied to drive plate 1138 maymove the drive plate toward button housing 1144 if the applied force islarge enough to compress washer springs 1142. Button housing 1144 may befixed in position by end cap 1152. The force applied to drive plate 1138may contact end 1170 of set shaft 1140 against arm 1172 of button latch1146. If the force applied to drive plate 1138 is large enough, end 1170will move arm 1172 toward end cap 1152 and rotate hook 1174 away frombutton 1150 to release the button. Button spring 1148 may force aportion of button 1150 above top surface 1178 of end cap 1152.

[0206] To calibrate a seater, activation mechanism 1106 may be coupledto calibrator 1180. A calibrator is shown schematically in FIG. 53. Inan embodiment, threading couples activation mechanism 1106 to calibrator1180. In other embodiments, quick connects or other types of connectorsmay couple activation mechanism 1106 to calibrator 1180. Calibrator 1180may include an internal force sensor. End 1162 of first drive rod 1132(shown in FIG. 51) may contact the force sensor. A user may squeezehandle 1130 of activation mechanism 1106 until button 1150 pops up abovetop surface 1178 of end cap 1152. The user may observe the amount offorce applied by the end to the sensor from display 1182. Display 1182may be an analog indicator or a digital indicator (such as an LCDdisplay). After button 1150 has popped up and handle 1130 has beenreturned to an initial position, the user may push the button downwardsso that a latch hook engages a portion of the button. If the forceneeded to release button 1150 is too small, set shaft 1140 (shown inFIG. 52) may be threaded into drive plate 1138 to decrease a length ofthe set shaft so that more compression of springs 1142 is requiredbefore the contact between the set shaft and latch will release thebutton. If the force needed to release button 1150 is too large, setshaft 1140 may be threaded out of drive plate 1138 to increase thelength of the set shaft so that less compression of springs 1142 isrequired before the contact between the set shaft and latch 1140 willrelease the button.

[0207] The length of set shaft 1140 that extends above drive plate 1138,shown in FIG. 52, may be adjusted by rotating the set shaft with a drivetool. The drive tool, which may be a hex wrench, may pass through button1150 and latch 1140 without disassembly of the seater. After adjustingset shaft 1140, the user may squeeze the handle to determine the amountof force needed to release button 1150 at the new setting of set shaft1140. The user may continue. adjusting set shaft 1140 until a desiredamount of force releases button 1150. The desired amount of force maydirectly correspond to an amount of force that needs to be applied tothe connectors and implant members to affix the connectors to theimplant members. When set shaft 1140 is positioned so that a properamount of force releases button 1150 when the seater handle is squeezed,the position of the set shaft may be fixed by rotating a setscrew todrive the setscrew into drive plate 1138 and against the set shaft. Thedesired amount of force to couple connectors to an implant member may bebetween about 800 pounds and about 1200 pounds, or between about 900pounds, and about 1100 pounds, or about 1000 pounds. The activationmechanism may provide a thirty- to fifty-fold or greater mechanicaladvantage to a grip of a user.

[0208] An embodiment of a seater may include a pop-up button to indicatewhen sufficient force has been applied to couple a connector orconnectors to an implant member. Other types of indicators may also beused instead of, or in conjunction with, a pop-up button. For example,an embodiment of a seater may include an indicator light that turns onwhen enough force is applied to affix a connector or connectors to animplant member. An embodiment of a seater may produce an audible noisewhen enough force is applied to affix a connector or connectors to animplant member. Other types of indicators may also be used.

[0209] An alternate embodiment of a seater is depicted in FIG. 54. Plateengager 1114 of attachment portion 1102 may be attached to drive rod1132 that extends through extender 1104 to activation mechanism 1106 ofseater 1100. Engaging activation mechanism 1106 of seater 1100 may movedrive rod 1132 from an initial position to a second position. When plateengager 1114 of seater 1100 is coupled to an implant member, applyingforce to activation mechanism 1106 may apply a force that retracts driverod 1132. Drive rod 1132 may retract plate engager 1114 relative tostationary connector engager 1112. Ends 1116 of connector engager 1112may apply a downward force against connectors in tapered slots ofimplant members as the implant members are moved upwards by plateengager 1114.

[0210] Connector engager 1112 of seater 1100 may have ends 1116 thatpress against the connectors positioned within the implant members.Connector engager 1112 may be sized to contact connectors that arespaced a set distance apart for a specific size of implant member.Connector engagers 1112 having various sizes corresponding to differentsizes of implant members may be provided in an instrumentation set. Theconnector engagers may be modular components that attach to extender1104 of seater 1100. In other embodiments, seaters may be integral unitsand complete seaters for each size of implant member included in aninstrumentation set may be provided in the instrumentation set.

[0211] Member engager 1114 may be shaped to engage a recessed portion ofan implant member. Member engager 1114 may include extensions 1120 thatare placed within openings 28 of implant member 12 (shown in FIG. 2).Member engager 1114 may also include stop surface 1188. Stop surface1188 may contact an anterior edge of an implant member to limit aninsertion depth of member engager 1114 within the implant member. Aftermember engager 1114 is coupled to an implant member, a retainer may beplaced between a second implant member and a back surface of the memberengager. The retainer may prevent unintentional removal of memberengager 1114 from the implant member.

[0212] Drive rod 1132 of seater 1100 may be coupled to plate engager1114 and extend through extender 1104 to activation mechanism 1106 ofthe seater. Drive rod 1132 may extend through collar 1190 proximate anopening at a top of extender 1104. Collar 1190 may limit a distancewhich drive rod 1132 extends through extender 1104 of the seater in aninitial position.

[0213] Drive rod 1132 may be attached to activation mechanism 1106through connection member 1192. Drive rod 1132 may be attached centrallyusing pins 1158 or may be welded to connection member 1192. A pair ofconnecting rods 1194 may be rotatably attached at an end using pins1158, or other fastening means, to connection member 1192 on oppositesides of drive rod 1132. Opposite ends of connecting rods 1194 may berotatably attached within slots 1196 proximate a base of a pair of grips1198 of activation mechanism 1106.

[0214] The pair of grips 1198 may be shaped to be easily graspable byone hand of a surgeon. Grips 1198 may be rotatably attached to extender1104 on opposite sides of collar 1190 and drive rod 1132 extending fromthe extender. FIG. 54 shows grips 1198 in an initial position. Springmembers 1200 may bias grips 1198 to the initial position. An end ofspring member 1200 may be affixed to an end of each of grips 1198opposite extender 1104 of the seater with fasteners 1202. Fasteners maybe, but are not limited to, screws, rivets, brads, and/or adhesive. Theopposite end of each spring member 1200 may slidably engage an upperportion of connecting rod 1194 proximate connection member 1192.

[0215] The distal end of one of grips 1198 may include kiss pin 1204.Kiss pin 1204 may contact the distal end of other grip 1198 when thegrips are squeezed together to a second position when activationmechanism 1106 of the seater is activated. Kiss pin 1204 may contactopposite grip 1198 when sufficient force is applied through the seaterto the implant to permanently lock the connectors to the implantmembers. The seater may apply a force of approximately 2250 Newtons (N)to each connector to affix (or “cold weld”) a connector within a taperedslot of an implant member to the implant member.

[0216] When grips 1198 are squeezed together to activate the seater,spring members 1200 may slide along connecting rods 1194 proximateconnection member 1192. Connecting rods 1194 may rotate within slots1196 proximate the base of grips 1198. An upper end of slots 1196 mayinhibit further rotation of connecting rods 1194 when kiss pin 1204 onthe end of one grip 1198 contacts the opposite grip. The ends ofconnecting rods 1194 rotatably attached to connection member 1192 mayrotate and force the connection member upward. The upward force onconnection member I 192 retracts drive rod 1132 attached centrally tothe connection member through extender 1104 of the seater. As such, animplant member coupled to the end of drive rod 1132 at the attachmentportion of the seater is forced upwards. Ends 1116 of connector engager1112 may contact and apply an opposing force against the connectors inthe tapered slots of the implant members as the implant member isretracted upward toward the extender. Sufficient force is appliedthrough the seater to the implant to permanently lock and affix theconnectors to the implant members.

[0217] As shown in FIG. 55, seater I100 may include retainer brackets1206. Retainer brackets 1206 may be attached to extender 1104. Retainer1300 may slide within retainer brackets 1206. Retainer brackets 1206 mayallow retainer and seater to be joined together to facilitate handlingof the retainer and seater during use. In some embodiments, spacer 1304may include a tapered surface that facilitates insertion of the spacerin a space between implant members. In some embodiments, member engager1114 of seater 1100 may include a stop that limits an insertion distanceof spacer 1304 between implant members.

[0218] An instrumentation set may include the instruments and devices toform an implant in a spinal fusion procedure. A surgeon may perform adiscectomy to remove a portion or all of disc 20 to form disc space 16between adjacent vertebrae 18. A prepared disc space is shown in FIG. 3.Instruments such as curettes, rongeurs, and bone shavers may be used toprepare disc space 16 for the implant. Vertebral surfaces that willcontact implant members 12 of implant 10 (shown in FIG. 1 and FIG. 2)may be cleaned of any cartilage or other tissue. The vertebral surfacesmay be shaped to substantially conform to outer surfaces of implantmembers to be placed against the vertebral surfaces.

[0219] A width and depth spacer, such as width and depth spacer 100depicted in FIG. 9, may be used to determine the proper width and depthof the disc space during the discectomy. Radiological images may betaken during the discectomy with spacer 100 positioned between thevertebrae to determine if disc material has been removed to form a discspace of the proper width and depth. A mark or marks may be scored orburned into a surface of a vertebra close to a center of an edge of thevertebra. The mark may be used as a reference mark to determine a properlateral position of the implant and instrumentation during formation ofthe implant. The disc space may be centered laterally and transverselybetween adjacent vertebrae. When an implant is formed, 70% or more ofeach vertebral surface may contact implant members of the implant.

[0220] A height spacer, such as height spacer 200 depicted in FIG. 10,may be used to determine a height of an implant to be formed in theprepared disc space between vertebrae. Height spacer 200 may be attachedto a slap hammer, such as slap hammer 900 depicted in FIG. 27. A properheight of an implant may correspond to the size of a height spacer thatis positioned within the disc space with three or four impacts of slide908 against a lower stop of slap hammer 900. The height spacer may beremoved from the disc space by impacting slap hammer slide 908 againstupper stop 910.

[0221] A pair of implant members may be selected depending on the sizeof the disc space created during the discectomy. Implant member orimplant members 12 that include sloped surfaces 22 (depicted in FIG. 1)may be selected to provide lordotic correction for adjacent vertebrae,if necessary. If lordotic adjustment of the vertebrae is not needed,implant members 12 with 0° of lordotic adjustment may be selected.Connectors 14 may be selected depending on the height of the implant tobe formed within the disc space.

[0222] Implant members may be attached to a spreader, such as spreader400 depicted in FIG. 36. The implant members may be inserted into theprepared disc space. If needed, an impact cap may be placed on thespreader, and insertion guides may be placed in the disc space tofacilitate insertion of the implant members into the disc space.

[0223] A separator, such as separator 300 depicted in FIG. 33, may beinserted into the spreader. Connectors may be positioned in sideopenings 328 prior to insertion of the separator into the spreader.Inserting the separator into the spreader may separate implant membersattached to the spreader to a desired separation distance. Duringinsertion of the separator into the spreader, protrusions of the implantmembers may enter into vertebral surfaces.

[0224] Depth gauges, such as depth gauge 800 depicted in FIG. 34, may beinserted into depth gauge passages in the separator. The depth gaugesmay dislodge the connectors from the side openings. The depth gauges mayposition the connectors in tapered slots of the implant members.

[0225] A slap hammer may be attached to the separator, as depicted inFIG. 46. The slap hammer may be used to remove the separator, spreader,and depth gauges from the patient. Implant members with connectorspositioned in tapered slots of the implant members may be left in thedisc space. Radiological images may be taken to ensure the implantmembers and connectors are laterally and transversely positionedproperly before locking the connectors into place.

[0226] A connector seater, such as connector seater 1100 depicted inFIG. 54, may be coupled to a first implant member. A retainer may bepositioned between a second implant member and the separator to inhibitseparation of the seater from the first implant member. Grips of theseater may be squeezed until kiss pin on a first grip contacts a secondgrip. When the kiss pin contacts the second grip, the connectors areaffixed to the first implant member. The retainer may be removed. Theseater may be disengaged from the first implant member and may beattached to the second implant member. The retainer may be positionedbetween the first implant member and the seater to inhibit removal ofthe seater from the second implant member. Grips of the seater may besqueezed until the kiss pin on the first grip contacts the second grip.The retainer and the seater may be removed from the patient. The implantis formed in the patient.

[0227] An optional backing plate, such as backing plate 60 depicted inFIG. 8, may be sized and inserted into the implant. Backing plate 60 maybe properly sized by cutting the backing plate along indentions 62.Backing plate 60 may be coupled to a positioning rod. In an embodiment,the positioning rod is a depth gauge. The positioning rod may be used toguide backing plate 60 between the implant members of the implant untiltabs 64 of the backing plates engage end walls of the implant members,such as end walls 66 of implant members 12 depicted in FIG. 5.

[0228] A bone awl may be used to perforate the surfaces to initiatebleeding of adjacent vertebrae through openings 28 in implant members12. Perforation of the surfaces may promote new bone growth. The spacebetween implant members 12 and connectors 14 of implant 10 may be packedwith bone growth material, such as bone growth material 26 depicted inFIG. 4. A covering, such as SURGICEL®, may be placed over the bonegrowth material to inhibit migration of bone growth material 26 fromimplant 10. The opening in the patient may be closed.

[0229] An advantage of forming an implant in a space between two boneportions, such as an implant between adjacent vertebrae, may be that theimplant members of the implant distract the bone portions to a desiredseparation distance without excess distraction of the bone. Avoidingover-distraction may allow muscles and ligaments adjacent to the implantto hold the implant between the bone portions. The implant members ofthe implant may also include protrusions that enter into adjacent boneportions to hold the implant in place. Connectors that join the implantmembers together may be compressed when a compressive load is placed onthe implant. The ability to compress the connectors may allowcompressive force to be applied to bone growth material placed betweenthe implant members. Applying compressive force to the bone growthmaterial may promote bone growth that fuses the two portions of bonetogether.

[0230] An advantage of forming an implant using spreader embodiments andseparator embodiments is that impaction applied to insert the implantmay minimize scarring, deformation, and/or fracturing of bone surfacesto which the implant is coupled. Implant members may be positioned in aprepared space before distracting the bone portions.

[0231] An advantage of forming an implant using spreader embodiments andseparator embodiments is that the insertion area needed for theinstrumentation may be kept to a minimum. Force applied between a pairof spreader holders allows outer surfaces of implant members to distractadjacent bone portions. Using the outer surfaces of the implant membersto distract the bone portions may eliminate a need to have a largesurgical opening to allow for room to leverage the adjacent boneportions to provide a desired separation distance between the boneportions.

[0232] An advantage of forming an implant between bone segments usingspreader embodiments and separator embodiments may be that insertion ofinstruments and implants may be performed above an incision in thepatient. The ability to insert devices and instrumentation above theincision may allow better visibility, more efficient use of availableworking space, a shorter procedure time, and better placement controlthan inserting devices at the level of bone portions being worked on.Implants may be inserted during an anterior procedure, a lateralprocedure, a posterior procedure, or other spinal fusion procedure.Inserting implants using an anterior procedure may advantageouslyminimize required bone removal and muscle retraction.

[0233] An advantage of forming an implant with certain spreaderembodiments and separator embodiments is that locking pins may be usedto couple implant members to the instrumentation during insertion of theimplant members within a patient. The locking pins may attach theimplant members to the spreader before the implant members are insertedinto the patient. The locking pins may inhibit undesired separation ofthe implant members from the spreader. The locking pins may also serveas guides during insertion of the separator into the spreader.

[0234] An advantage of forming an implant with instrumentationembodiments is that the formed implant may be formed to a desired shape.For example, if the implant is a spinal implant, the implant members mayhave sloped surfaces so that the formed implant provides desiredlordotic adjustment of adjacent vertebrae. Further advantages of usinginstrumentation to insert an implant may include that theinstrumentation is sturdy, durable, lightweight, safe, simple,efficient, and reliable; yet the instrumentation may also be easy tomanufacture and use.

[0235] Further modifications and alternative embodiments of variousaspects of the invention will be apparent to those skilled in the art inview of this description. Accordingly, this description is to beconstrued as illustrative only and is for the purpose of teaching thoseskilled in the art the general manner of carrying out the invention. Itis to be understood that the forms of the invention shown and describedherein are to be taken as examples of embodiments. Elements andmaterials may be substituted for those illustrated and described herein,parts and processes may be reversed, and certain features of theinvention may be utilized independently, all as would be apparent to oneskilled in the art after having the benefit of this description of theinvention. Changes may be made in the elements described herein withoutdeparting from the spirit and scope of the invention as described in thefollowing claims.

What is claimed is:
 1. An instrument set, comprising: a spreaderconfigured to couple to and insert members of an implant between bonestructures; and a separator configured to be inserted into the spreaderto establish a separation distance between the members and facilitateinsertion of a connector between the members.
 2. The instrument set ofclaim 1, further comprising a depth gauge configured to position theconnector at a desired position between the members.
 3. The instrumentset of claim 2, wherein the depth gauge comprises an end configured toengage a backing plate to facilitate insertion of the backing platebetween members positioned between the bone structures.
 4. Theinstrument set of claim 1, further comprising a mallet.
 5. Theinstrument set of claim 1, further comprising locking pins configured tosecure the members to the spreader.
 6. The instrument set of claim 1,further comprising a slap hammer.
 7. The instrument set of claim 1,further comprising an extender configured to provide an impact surfacefor driving the separator into the spreader.
 8. The instrument set ofclaim 1, further comprising an end cap for the spreader.
 9. Theinstrument set of claim 1, further comprising a width and depth spacer.10. The instrument set of claim 1, further comprising a height spacer.11. The instrument set of claim 1, further comprising a backing plateconfigured to be positioned between members inserted between the bonestructures.
 12. The instrument set of claim 1, further comprising aninsertion guide configured to facilitate insertion of members coupled tothe spreader between the bone structures.
 13. The instrument set ofclaim 1, further comprising an insertion guide configured to facilitateinsertion of members coupled to the spreader between the bonestructures, wherein the insertion guide comprises a first arm, a secondarm, and a shaft; and wherein the members are positionable between thefirst arm and the second arm after removal of the shaft.
 14. Theinstrument set of claim 1, further comprising a seater configured toapply force to the connector and to a first member that fixes theposition of the connector relative to the first member.
 15. Theinstrument set of claim 14, further comprising a retainer configured tobe positioned between a second member and the seater to inhibit releaseof the seater from the first implant member.
 16. The instrument set ofclaim 14, further comprising a retainer configured to be positionedbetween a second member and the seater, and wherein the seater comprisesa bracket configured to hold a portion of the retainer.
 17. Theinstrumentation set of claim 1, further comprising forceps, the forcepsconfigured to hold a connector so that the connector can be positionedand released into the separator.
 18. The instrument set of claim 1,further comprising members.
 19. The instrument set of claim 1, furthercomprising members, wherein each implant member of a first set of themembers have a surface area that contacts or is adjacent to bonestructure when inserted into a patient that is larger than acorresponding surface area of each member of a second set of themembers.
 20. The instrument set of claim 1, further comprising members,wherein at least one member of the members has a surface that allows animplant formed from the at least one member to have an anterior heightthat is different than a posterior height.
 21. The instrument set ofclaim 1, further comprising connectors configured to couple memberstogether.
 22. An instrument set for forming an implant between bonestructures, comprising: a plurality of implant members; a plurality ofconnectors; at least one spreader configured to couple to and insertimplant members between the bone structures; and at least one separatorconfigured to establish a separation distance between implant memberscoupled to the at least one spreader, wherein the at least one separatorfacilitates placement of connectors between implant members insertedbetween the bone structures.
 23. The instrument set of claim 22, furthercomprising a seater configured to fix the position of connectorsrelative to implant members that are inserted between the bonestructures.
 24. The instrument set of claim 23, further comprising atleast one retainer configured to be positioned between an implant memberand the seater.
 25. The instrument set of claim 23, wherein the seatercomprises a bracket to allow a retainer to be coupled to the seaterduring use.
 26. The instrument set of claim 22, further comprising atleast one depth gauge configured to establish an initial position of aconnector relative to implant members that are positioned between thebone structures.
 27. The instrument set of claim 22, further comprisingat least one slap hammer.
 28. The instrument set of claim 22, furthercomprising at least one locking pin configured to secure implant membersto the spreader.
 29. The instrument set of claim 22, further comprisingat least one width and depth spacer.
 30. The instrument set of claim 22,further comprising a plurality of height spacers.
 31. The instrument setof claim 22, further comprising at least one insertion guide.
 32. Theinstrument set of claim 22, further comprising an end cap for aspreader, the end cap configured to provide an impact surface fordriving the spreader between the bone structures.
 33. The instrument setof claim 22, further comprising at least one backing plate.
 34. Theinstrument set of claim 22, further comprising at least one extenderconfigured to facilitate insertion of instruments between bonestructures.
 35. The instrument set of claim 22, further comprisingforceps configured to hold and release connectors.
 36. The instrumentset of claim 22, wherein at least one separator comprises connectorpassages configured to guide connectors to implant members coupled tothe at least one spreader.
 37. The instrument set of claim 22, whereinthe plurality of implant members include at least one implant memberthat is configured to allow for the formation of an implant that has ananterior height that differs from a posterior height.
 38. The instrumentset of claim 22, wherein the plurality of implant members include afirst set of implant members that have a larger surface configured tocontact or be adjacent to a vertebral surface than a surface areaconfigured to contact or be adjacent to a vertebral surface of a secondset of implant members of the plurality of implant members.
 39. Theinstrument set of claim 22, wherein the plurality of connectors comprisea first set of two connectors, each of the first set of connectorshaving a height, and a second set of two connectors, each of the secondset of connectors having a height, and wherein the height of the firstset of connectors is larger than the height of the second set ofconnectors.
 40. A separator, comprising: a body; at least one passagethrough the body; and wherein the body is configured to separate membersof an implant in a prepared space between adjacent bone structures. 41.The separator of claim 40, wherein the body comprises a central portionthat is open to reduce an overall weight of the separator.
 42. Theseparator of claim 40, further comprising an attachment mount.
 43. Theseparator of claim 42, wherein the attachment mount is configured tocouple to an insertion/removal tool.
 44. The separator of claim 43,wherein the insertion/removal tool comprises a slap hammer.
 45. Theseparator of claim 40, wherein at least one passage through the body isconfigured to allow a connector of a specific size to pass through. 46.The separator of claim 40, wherein at least one passage through the bodyis configured to allow a locking pin to pass through.
 47. The separatorof claim 40, further comprising a ridge to limit an insertion depth ofthe separator into a spreader.
 48. The separator of claim 47, whereinthe ridge mates with a ledge in an opening of the spreader.
 49. Theseparator of claim 47, wherein the body comprises an end configured toseparate members of the implant coupled to the spreader.
 50. Theseparator of claim 49, wherein the end comprises a central portionbetween two outer arms.
 51. The separator of claim 50, wherein thecentral portion comprises chamfered edges to facilitate insertion of theseparator into the spreader.
 52. The separator of claim 50, wherein thetwo outer arms inhibit rotational motion of the separator when fullyinserted into the spreader.
 53. The separator of claim 50, wherein thecentral portion and two arms define a guide for insertion of theseparator into the spreader.
 54. The separator of claim 49, whereininsertion of the end between the members of the implant inhibitsover-distraction of the adjacent bone structures.
 55. The separator ofclaim 40, further comprising a groove configured to guide the separatorbetween members of the implant coupled to holders of a spreader duringinsertion of the separator into the spreader.
 56. The separator of claim40, wherein the attachment mount comprises an impact surface forimpacting the separator between members of the implant coupled to aspreader.
 57. The separator of claim 40, wherein the body comprisesopenings for engaging a retention mechanism of a spreader to inhibitmovement of the separator when fully inserted into the spreader.
 58. Theseparator of claim 40, wherein a connector is inserted into an openingin at least one passage of the body.
 59. The separator of claim 40,wherein a connector is inserted into a side opening proximate aninsertion end of at least one passage of the body prior to inserting theseparator into a spreader.
 60. The separator of claim 59, wherein theside opening of at least one passage is configured to allow insertion ofthe connector in only one direction.
 61. The separator of claim 59,wherein the side opening comprises a pair of detents to inhibitunintentional release of the connector from the side opening.
 62. Theseparator of claim 40, further comprising an opening at a top portion ofeach passage to accept a gauge configured to extend through and releasea connector from the passage.
 63. The separator of claim 62, wherein thegauge is configured to position the connector to a correct depth withinslots between members of an implant.
 64. The separator of claim 62,wherein the gauge is impacted into the passage with a mallet.
 65. Theseparator of claim 62, wherein the opening comprises a ledge to limit aninsertion depth of the gauge in the passage of the separator.
 66. Aseparator, comprising: a body configured to establish a separationdistance between implant members; a first passage in a portion of thebody, the first passage configured to allow a connector to pass from thebody into portions of implant members; and a connector inhibitor in thefirst passage, the inhibitor configured to inhibit undesired release ofa connector positioned in the first passage.
 67. The separator of claim66, further comprising a second passage in communication with the firstpassage, wherein an instrument positioned through in the second passageis configured to release a connector positioned in the first passageduring use.
 68. The separator of claim 66, wherein the body comprises afirst guide, and wherein the first guide is configured to couple to aportion of a spreader during use to facilitate placement of the bodyrelative to the spreader.
 69. A spreader for forming an implant betweenadjacent bone structures, comprising: a body; and a first holder and asecond holder configured to couple to inner surfaces of implant members;wherein the body is configured to insert the first and second holderscoupled to the implant members in an initial position into a preparedspace between adjacent bone structures.
 70. The spreader of claim 69,wherein the first and second holders comprise removably attachablemounts to couple to the inner surfaces of the implant members to thefirst and second holders.
 71. The spreader of claim 69, wherein thefirst holder is an integral part of the body of the spreader.
 72. Thespreader of claim 69, wherein the first and second holders are anintegral part of the body of the spreader.
 73. The spreader of claim 69,wherein the first and second holders comprise at least one protrusion onan outer surface configured to press-fit into an opening of the implantmembers to couple the implant members to the first and second holders.74. The spreader of claim 69, wherein the first and second holderscomprise tongues configured to engage recesses in the inner surfaces ofthe implant members.
 75. The spreader of claim 69, wherein the first andsecond holders comprise raised portions to engage recesses in the innersurfaces of the implant members.
 76. The spreader of claim 69, whereinthe first and second holders comprise slots configured to deflect toallow a press-fit engagement of the first and second holders to theimplant members.
 77. The spreader of claim 76, wherein the slots arefurther configured to inhibit a change in spring properties of the firstand second holders.
 78. The spreader of claim 69, wherein the first andsecond holders comprise a slot, the slot extending to the end of thefirst and second holders, and wherein the slot is configured to allowfor deflection of the first holder and the second holder to allow apress-fit engagement of the first and second holders to the implantmembers.
 79. The spreader of claim 69, wherein the first and secondholders comprise dovetailed sidewalls configured to engage a recess inthe inner surface of the implant members.
 80. The spreader of claim 69,wherein the first and second holders comprise straight sidewallsconfigured to engage a recess in the inner surface of the implantmembers.
 81. The spreader of claim 69, wherein the first and secondholders comprise a stop, the stop configured to limit an insertion depthof the first and second holders into the implant members.
 82. Thespreader of claim 69, wherein the first holder comprises a compressionmember configured to apply a force against a recess in the inner surfaceof an implant member to frictionally couple the implant member to thefirst holder.
 83. The spreader of claim 82, wherein the compressionmember comprises a stop configured to limit an insertion depth of thefirst and second holders into the implant members.
 84. The spreader ofclaim 82, wherein the compression member is configured to engage anopening in the recess of the implant member to provide an interferencecoupling of the implant member to the first holder.
 85. The spreader ofclaim 69, further comprising a locking pin, wherein a portion of thelocking pin is insertable through a slot in the first holder and througha slot in the second holder to reside in slots of the implant membersduring use.
 86. The spreader of claim 85, wherein the locking pincomprises a tapered portion to slide through aligned slots of the firstand second holders and engage the slots of the implant members.
 87. Thespreader of claim 86, wherein the tapered portion of the locking pincomprises a compression slot, the compression slot configured to becompressed when engaging the slots of the implant members tofrictionally secure the locking pins to the implant members during use.88. The spreader of claim 85, wherein the locking pin is configured topass through passages of a separator to guide the separator duringinsertion of the separator into the spreader.
 89. The spreader of claim69, wherein the first holder and the second holder comprise depthmarkings configured to indicate a depth that implant members coupled tothe first holder and the second holder are inserted between adjacentbone structures.
 90. The spreader of claim 69, wherein the bodycomprises a depth indicator to indicate a depth that implant memberscoupled to the first holder and the second holder are inserted betweenadjacent bone structures.
 91. The spreader of claim 69, wherein the bodycomprises a pair of opposing channel members configured to couple thefirst and second holders to the body of the spreader.
 92. The spreaderof claim 91, wherein inner surfaces of the pair of channel members areseparated by a distance to allow insertion of a separator between thefirst holder and the second holders and the pair of channel members. 93.The spreader of claim 91, wherein the channel members inhibit lateraland rotational movement of a separator inserted between the first andsecond holders.
 94. The spreader of claim 69, wherein the first holderand the second holder are angled such that there is substantially noseparation distance between an end of the first holder and an end of thesecond holder when in an initial position.
 95. The spreader of claim 94,further comprising a spring member configured to hold the first andsecond holders in the initial position.
 96. The spreader of claim 95,wherein a first end of the spring member is attached to the body of thespreader and a second end contacts the second holder.
 97. The spreaderof claim 69, wherein the body comprises an opening configured to allowinsertion of a device into the spreader.
 98. The spreader of claim 97,wherein the opening in the body comprises a ledge to limit an insertiondepth of the device into the spreader.
 99. The spreader of claim 97,wherein the body further comprises at least one retention mechanismconfigured to inhibit movement of the device inserted into the openingin the body.
 100. The spreader of claim 97, wherein the device comprisesa separator to separate the implant members coupled to the spreader.101. The spreader of claim 100, wherein the separator comprises a ridgethat mates with a ledge in the opening to limit an insertion depth ofthe separator into the spreader.
 102. The spreader of claim 100, whereinthe separator is configured to couple to a slap hammer to remove theseparator and spreader from between the adjacent bone structures. 103.The spreader of claim 97, wherein the device comprises an end cap toprovide an impact surface for driving the spreader between adjacent bonestructures.
 104. The spreader of claim 103, wherein the end cap andspreader comprise a limit system that limits an insertion depth of theimpact end cap into the body of the spreader.
 105. The spreader of claim69, wherein the first holder and the second holders comprise slopedinner surfaces, the sloped inner surfaces configured to allow controlledseparation of the implant members coupled to the spreader by a separatorinserted between the first and second holders.
 106. The spreader ofclaim 69, wherein the first holder comprises a limiter to limit aninsertion depth of a separator into the spreader.
 107. The spreader ofclaim 69, wherein the implant members comprise a portion of a spinalfusion device.
 108. The spreader of claim 69, further comprising ahandle for positioning the holders between adjacent bone structures.109. A spreader, comprising: a body; a locking mechanism in the bodyconfigured to inhibit removal of a separator inserted into the body; afirst arm extending from the body, the first arm having a first holder,wherein the first holder is configured to couple to an implant member;and a second arm extending from the body, the second arm having a secondholder, wherein the second holder is configured to couple to an implantmember.
 110. The spreader of claim 109, a portion of the first arm isconfigured to interact with a portion of a separator to maintainalignment of the separator relative to the first arm during use.
 111. Aseater for forming an implant between adjacent bone structures,comprising: an attachment end, comprising: a first engager configured tocouple to an implant member of the implant; and a second engagerconfigured to engage a connector coupled to the implant member; and anactivator configured to move the first engager relative to the secondengager to lock the connector to the implant member.
 112. The seater ofclaim 111, wherein the seater applies a force to the connectors andimplant member to drive a portion of the connector into a slot of theimplant member with enough force to inhibit subsequent removal of theportion from the slot.
 113. The seater of claim 111, wherein a forcethat moves the first engager relative to the second engager is aboutthirty to about one hundred times greater than a force applied to theactivator.
 114. The seater of claim 111, wherein the seater applies atleast about 1600 N of force is applied to move the first engagerrelative to the second engager.
 115. The seater of claim 111, whereinuse of the activator moves the first engager.
 116. The seater of claim111, wherein use of the activator moves the second engager.
 117. Theseater of claim 111, further comprising an indicator that allows a userto know when sufficient force is applied to fix the connector to theimplant member.
 118. The seater of claim 117, wherein the indicatorcomprises a pin attached to a first member of the activator thatcontacts a second member of the activator to indicate when sufficientforce is applied to fix the connector to the implant member.
 119. Theseater of claim 117, wherein the indicator comprises a button thatextends from a portion of the seater when sufficient force is applied tofix the connector to the implant member.
 120. The seater of claim 111,further comprising at least one bracket coupled to the seater, the atleast one bracket configured to allow for placement of an end portion ofa retainer at a desired position relative to the first engager and thesecond engager.
 121. The seater of claim 111, wherein the first engageris configured to couple to at least one opening in the implant member.122. The seater of claim 111, wherein the first engager is removablyattached to the seater.
 123. A seater, comprising: a first engagerconfigured to couple to a first implant member; a second engagerconfigured to engage a connector, wherein the connector couples thefirst implant member to a second implant member; an activator configuredto move the first engager relative to the second engager to fix theconnector in the first implant member.
 124. The seater of claim 123,further comprising a shaft that couples the activator to the secondengager, and a spacer in working relation to the shaft, wherein aportion of the spacer is positionable between the first implant memberand the second implant member when the first engager is moved relativeto the second engager.
 125. A system for forming an implant betweenadjacent bone structures, comprising: a spreader comprising holders,wherein each holder is configured to couple to an inner surface of animplant member of the implant; at least one separator comprisingpassages for inserting connectors between the implant members; and aseater; wherein the separator is configured to be inserted betweencoupled implant members inserted between the adjacent bone structures bythe spreader, and wherein the seater is configured to couple an implantmember of the implant and lock connectors inserted between the implantmembers by the separator to the coupled implant member.
 126. The systemof claim 125, wherein a holder of the spreader comprises dovetailedsidewalls configured to engage a recess in the inner surface of animplant member.
 127. The system of claim 125, wherein a holder of thespreader comprise straight sidewalls configured to engage a recess inthe inner surface of an implant member.
 128. The system of claim 125,wherein a holder of the spreader comprise a compression member, thecompression member configured to apply a force against a recess in theinner surface of an implant member to frictionally couple the implantmember to the holder.
 129. The system of claim 128, wherein thecompression member comprises a ridge configured to limit an insertiondepth of the holder into the implant member.
 130. The system of claim128, wherein the compression member is configured to engage an openingin the recess of the implant member to provide an interference couplingof the implant members to the holder.
 131. The system of claim 125,wherein the spreader comprises a depth indicator to indicate aninsertion depth into a space between adjacent bone structures of implantmembers coupled to the spreader.
 132. The system of claim 131, whereinthe depth indicator comprises markings.
 133. The system of claim 125,wherein the holders of the spreader are angled such that there issubstantially no separation distance between ends of the holders coupledto implant members when the spreader is in an initial position.
 134. Thesystem of claim 125, wherein the holders of the spreader comprise a stopsurface to limit an insertion depth of a separator into the spreader.135. The system of claim 125, wherein a body of a spreader comprises anopening configured to allow insertion of a separator of the at least oneseparators into the spreader.
 136. The system of claim 135, wherein theseparator of the at least one separators comprises an impact surface.137. The system of claim 135, wherein the opening in the body comprisesa ledge to limit an insertion depth of the separator into the spreader.138. The system of claim 135, wherein the body further comprises atleast one retention mechanism configured to inhibit movement of theseparator relative to the spreader when the separator is inserted intothe opening in the body.
 139. The system of claim 135, wherein theopening is configured to allow for insertion of an end cap, and whereinthe end cap provides an impact surface for driving the spreader betweenbone structures.
 140. The system of claim 139, wherein an insertiondepth of the end cap into the spreader is limited.
 141. The system ofclaim 139, wherein the body comprises at least one retention mechanismconfigured to inhibit movement of the end cap when the end cap isinserted into the opening in the body.
 142. The system of claim 125,wherein the holders of the spreader comprise sloped inner surfacesconfigured to allow desired separation of implant members that arecoupled to the spreader when a separator is inserted between theholders.
 143. The system of claim 125, wherein the adjacent bonestructures are vertebrae.
 144. The system of claim 125, wherein theimplant members comprise a portion of a spinal fusion device.
 145. Thesystem of claim 125, wherein the passages of a separator of the at leastone separator are configured to allow a selected size of connector topass through.
 146. The system of claim 145, wherein the selected size ofconnector is a size configured to form an implant with a height rangingfrom greater than about 8 mm to less than about 24 mm.
 147. The systemof claim 125, wherein the separator comprises an end configured toestablish a separation distance between implant members coupled to thespreader.
 148. The system of claim 147, wherein the end comprises acentral portion between two outer arms.
 149. The system of claim 148,wherein the central portion comprises chamfered edges to facilitateinsertion of the separator into the spreader.
 150. The system of claim148, wherein the two outer arms inhibit rotational motion of theseparator when the separator is inserted into the spreader.
 151. Thesystem of claim 148, wherein the central portion and two arms define aguide for insertion of the separator into the spreader.
 152. The systemof claim 148, wherein insertion of the end between the implant memberscoupled to the spreader inhibits over-distraction of the adjacent bonestructures.
 153. The system of claim 125, wherein insertion of theseparator between the implant members coupled to the spreader inhibitsover-distraction of the adjacent bone structures.
 154. The system ofclaim 125, wherein the separator comprises a groove configured to guidethe separator between the implant members coupled to the holders of thespreader.
 155. The system of claim 125, wherein the separator comprisesopenings for engaging a retention mechanism of the spreader to inhibitmovement of the separator when the separator is inserted into thespreader.
 156. The system of claim 125, wherein connectors are insertedinto side openings proximate an insertion end of the passages of theseparator prior to inserting the separator into the spreader.
 157. Thesystem of claim 156, wherein the side openings of the passages areconfigured to allow insertion of a connector in only one direction. 158.The system of claim 156, wherein each side opening comprises a detentsto inhibit undesired release of connectors from the side openings. 159.The system of claim 125, wherein the separator further comprisesopenings at a top portion of each passage to accept a gauge configuredto extend through and release a connector. from the passage.
 160. Thesystem of claim 159, wherein the gauge is configured to position theconnector to a correct depth within slots between the implant members.161. The system of claim 125, wherein the seater applies a force to theconnectors and implant members to drive the connectors into slots of theimplant members.
 162. The system of claim 125, wherein the seatercomprises an indicator to inform a user when a desired amount of forceis applied to fix the connectors to the implant members.
 163. The systemof claim 162, wherein the indicator comprising a pin on a first arm ofan activator that is configured to contact a portion of a second arm ofthe activator.
 164. The system of claim 125, further comprising aretainer positionable between the seater and an implant member duringuse of the seater.
 165. The system of claim 164, wherein the seatercomprises at least one bracket configured to hold a portion of theretainer to facilitate positioning of the retainer during use of theseater.
 166. A method of forming an implant between adjacent bonestructures, comprising; inserting a pair of implant members a spacebetween bone structures; separating the implant members to a desiredseparation distance; inserting connectors between the pair of implantmembers; and locking the connectors to the pair of implant members. 167.The method of claim 166, wherein the adjacent bone structures comprisevertebrae.
 168. The method of claim 167, wherein the space is preparedduring a discectomy that removes at least a portion of a disc betweenvertebrae.
 169. The method of claim 167, wherein the implant memberscomprise implant members of a spinal implant.
 170. The method of claim166, wherein the pair of implant members are coupled to holders of aspreader for insertion in the space between the adjacent bonestructures.
 171. A method for forming an implant between bonestructures, comprising: inserting a pair of implant members into a spacebetween the bone structures; joining the implant members together with aconnector; and locking the connector to the implant members.
 172. Themethod of claim 171, wherein inserting the pair of implant memberscomprises: coupling implant members to a portion of a spreader; andinserting the portion of the spreader into the space.
 173. The method ofclaim 171, wherein inserting the pair of implant members comprises:coupling implant members to a portion of a spreader; placing insertionguides adjacent to the bone structures; inserting the portion of thespreader between the insertion guides so that the implant members arepositioned between the bone members; and removing the insertion guides.174. The method of claim 171, wherein preparing the space comprisesperforming a discectomy to remove at least a portion of a disc betweenthe vertebrae.
 175. The method of claim 171, further comprising leavingthe adjacent surfaces of the vertebrae intact.
 176. The method of claim171, wherein the proper size of the space allows an implant to contactapproximately 70% of a surface of the adjacent vertebrae.
 177. Themethod of claim 171, further comprising selecting the pair of implantmembers depending on a desired lordotic alignment of the adjacentvertebrae.
 178. The method of claim 171, wherein the pair of implantmembers is selected from a plurality of implant members of differentlordotic angles.
 179. The method of claim 171, wherein the pair ofimplant members comprise protrusions on an outer surface to engagesurfaces of the adjacent vertebrae.
 180. The method of claim 171,wherein a spacer is used to determine a proper width and depth of thespace between the adjacent vertebrae.
 181. The method of claim 180,further comprising using radiological images of the spacer positionedbetween the adjacent bone structures to determine the proper width anddepth of the space between the adjacent vertebrae.
 182. The method ofclaim 171, further comprising marking the adjacent bone structures todetermine a proper lateral position of the implant.
 183. The method ofclaim 171, wherein a spacer is used to determine a proper height of thespace between the adjacent vertebrae.
 184. The method of claim 171,further comprising selecting the pair of implant members from aplurality of implant members depending on the size of the preparedspace.
 185. The method of claim 171, further comprising selecting theconnectors from a plurality of connectors depending on a height of theimplant to be formed.
 186. The method of claim 171, wherein the pair ofimplant members are coupled to member holders of a spreader forinsertion in the space between the adjacent vertebrae.
 187. The methodof claim 186, wherein the member holders are press-fit into openings ofthe pair of implant members.
 188. The method of claim 186, furthercomprising using a mallet to impact an impact cap coupled to thespreader to insert the spreader into the space between the adjacentvertebrae.
 189. The method of claim 186, further comprising separatingthe implant members coupled to the spreader between the adjacentvertebrae with a separator inserted into the spreader.
 190. The methodof claim 189, wherein the separator is configured to distract theimplant members to a desired separation distance of the adjacentvertebrae.
 191. The method of claim 189, wherein the spreader comprisesa ledge that mates with a ridge of the separator to limit an insertiondepth of the separator within the spreader.
 192. The method of claim189, wherein an indicator indicates a proper depth of the separatorwithin the spreader.
 193. The method of claim 192, wherein the indicatorcomprises observing when top surfaces of the separator and spreader areflush with each other.
 194. The method of claim 189, further comprisingusing a mallet to impact the separator into the spreader.
 195. Themethod of claim 189, wherein the separator comprises passages configuredto guide a selected size of connectors in a proper direction to bepositioned between the implant members when separated.
 196. The methodof claim 195, wherein a depth gauge is configured to fit within thepassages of the separator to push the connectors to a proper depth intotapered slots of the pair of implant members.
 197. The method of claim196, wherein the passages of the separator comprise a ledge that mateswith a ridge of the depth gauge to limit an insertion depth of the depthgauge within the separator.
 198. The method of claim 196, wherein anindicator indicates a proper depth of the depth gauge in the separator.199. The method of claim 198, wherein the indicator comprises topsurfaces of the depth gauge and separator flush with each other. 200.The method of claim 189, further comprising removing the separator andspreader together from between the adjacent vertebrae using a slaphammer coupled to the separator.
 201. The method of claim 171, furthercomprising inserting insertion guides within the space to protectscoring of surfaces of the adjacent vertebrae during insertion of thepair of implant members into the space.
 202. The method of claim 171,further comprising using radiological images to ensure the implantmembers and inserted connectors are laterally and transverselypositioned properly in the space between the adjacent vertebrae. 203.The method of claim 171, further comprising locking the connectorsbetween the pair of implant members with a cold weld.
 204. The method ofclaim 171, further comprising using a seater configured to couple to oneof the implant members inserted between the adjacent vertebrae to lockthe connectors to the coupled implant member.
 205. The method of claim204, further comprising inserting a retainer in a space between theseater coupled to the implant member and the other implant member toinhibit removal of the seater from the coupled implant member.
 206. Themethod of claim 204, wherein the seater comprises engagers configured toapply a force to the connectors to lock the connectors to the implantmember.
 207. The method of claim 171, further comprising positioning abacking plate at a posterior end between the inserted pair of implantmembers.
 208. The method of claim 171, further comprising perforatingsurfaces of the adjacent vertebrae through opening in the pair ofimplant members with a bone awl.
 209. The method of claim 171, furtherinserting bone growth material between the pair of implant members. 210.A connector for an implant, comprising: a body having a first end and asecond end, wherein the body is formed of a substantially rigidmaterial, and wherein the body comprises at least one opening configuredto allow compression of the body when a compressive load is applied tothe body; and a limiter coupled to the body, the limiter configured tolimit a distance of travel of the first end towards the second end. 211.The connector of claim 210, wherein a plurality of openings are formedin the body to allow for compression of the body when a compressive loadis applied to the body, and wherein the plurality of openings form an“X” pattern in the body.
 212. An implant, comprising: a first implantmember; a second implant member; and a connector insertable between thefirst implant member and the second implant member, wherein theconnector comprising a body having an opening that allows the body tocompress when a compressive load is applied to the first implant memberand the second implant member, and a limiter configured to limit adistance of travel of a first end of the body towards a second end ofthe body.
 213. The implant of claim 212, wherein the first implantmember includes a slot, wherein the second implant member includes aslot, wherein the first end of the body is configured to insert into theslot of the first implant member to join together the first member andthe connector, and wherein the second end of the connector is configuredto insert into the slot of the second implant member to join togetherthe second member and the connector.
 214. An implant for separating bonestructures, comprising: a pair of implant members configured to coupleto the bone structures; and a connector configured to join the pair ofimplant members together, the connector comprising: a flexible memberconfigured to allow a reduction in distance separating the pair ofimplant members when the implant members are subjected to a compressiveload, the flexible member having a first portion separated from a secondportion by a gap; and a limiter positioned in the gap, the limiterconfigured to inhibit reduction of the formed implant beyond apredetermined distance.
 215. The implant device of claim 214, whereinthe pair of implant members and the pair of connectors comprise a spinalimplant.
 216. The implant device of claim 214, wherein at least aportion of the implant members comprises a biocompatible material. 217.The implant device of claim 214, wherein at least a portion of outersurfaces of the implant members is configured to promoteosseointegration of the implant members and adjacent bone structures.218. The implant device of claim 214, wherein an outer surface of theimplant members comprises curvature to substantially conform to a shapeof surfaces of adjacent bone structures.
 219. The implant device ofclaim 214, wherein an implant member comprises a sloped outer surface.220. The implant device of claim 214, wherein an inner surface of eachimplant members comprises a recessed surface, wherein at least oneangled wall defines each recessed surface, and wherein the angled wallsare configured to engage a spreader that allows the implant members tobe inserted between vertebrae.
 221. A method of forming a connector foran implant, comprising: removing material from a blank to provideflexibility to the material of the blank; coupling a limiter to theblank to limit the amount of flexibility the blank; and forming ends ofthe connector so the ends are configured to couple to implant members.